Change search
Refine search result
12 1 - 50 of 86
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Abellán, F. J.
    et al.
    Indebetouw, R.
    Marcaide, J. M.
    Gabler, M.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Spyromilio, J.
    Burrows, D. N.
    Chevalier, R.
    Cigan, P.
    Gaensler, B. M.
    Gomez, H. L.
    Janka, H. -Th.
    Kirshner, R.
    Larsson, J.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Matsuura, M.
    McCray, R.
    Ng, C. -Y.
    Park, S.
    Roche, P.
    Staveley-Smith, L.
    van Loon, J. Th.
    Wheeler, J. C.
    Woosley, S. E.
    Very Deep inside the SN 1987A Core Ejecta: Molecular Structures Seen in 3D2017In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 842, no 2, article id L24Article in journal (Refereed)
    Abstract [en]

    Most massive stars end their lives in core-collapse supernova explosions and enrich the interstellar medium with explosively nucleosynthesized elements. Following core collapse, the explosion is subject to instabilities as the shock propagates outward through the progenitor star. Observations of the composition and structure of the innermost regions of a core-collapse supernova provide a direct probe of the instabilities and nucleosynthetic products. SN 1987A in the Large Magellanic Cloud is one of very few supernovae for which the inner ejecta can be spatially resolved but are not yet strongly affected by interaction with the surroundings. Our observations of SN 1987A with the Atacama Large Millimeter/submillimeter Array are of the highest resolution to date and reveal the detailed morphology of cold molecular gas in the innermost regions of the remnant. The 3D distributions of carbon and silicon monoxide (CO and SiO) emission differ, but both have a central deficit, or torus-like distribution, possibly a result of radioactive heating during the first weeks (nickel heating). The size scales of the clumpy distribution are compared quantitatively to models, demonstrating how progenitor and explosion physics can be constrained.

  • 2. Alp, Dennis
    et al.
    Larsson, Josefin
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Indebetouw, Remy
    Jerkstrand, Anders
    Ahola, Antero
    Burrows, David
    Challis, Peter
    Cigan, Phil
    Cikota, Aleksandar
    Kirshner, Robert P.
    van Loon, Jacco Th.
    Mattila, Seppo
    Ng, C. -Y.
    Park, Sangwook
    Spyromilio, Jason
    Woosley, Stan
    Baes, Maarten
    Bouchet, Patrice
    Chevalier, Roger
    Frank, Kari A.
    Gaensler, B. M.
    Gomez, Haley
    Janka, Hans-Thomas
    Leibundgut, Bruno
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Marcaide, Jon
    Matsuura, Mikako
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Sonneborn, George
    Staveley-Smith, Lister
    Zanardo, Giovanna
    Gabler, Michael
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Wheeler, J. Craig
    The 30 Year Search for the Compact Object in SN 1987A2018In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 864, no 2, article id 174Article in journal (Refereed)
    Abstract [en]

    Despite more than 30 years of searching, the compact object in Supernova (SN) 1987A has not yet been detected. We present new limits on the compact object in SN 1987A using millimeter, near-infrared, optical, ultraviolet, and X-ray observations from ALMA, VLT, HST, and Chandra. The limits are approximately 0.1 mJy (0.1 x 10(-26) erg s(-1) cm(-2) Hz(-1)) at 213 GHz, 1 L-circle dot (6 x 10(-29) erg s(-1) cm(-2) Hz(-1)) in the optical if our line of sight is free of ejecta dust, and 10(36) erg s(-1) (2 x 10(-30) erg s(-1) cm(-2) Hz(-1) ) in 2-10 keV X-rays. Our X-ray limits are an order of magnitude less constraining than previous limits because we use a more realistic ejecta absorption model based on three-dimensional neutrino-driven SN explosion models. The allowed bolometric luminosity of the compact object is 22 L-circle dot if our line of sight is free of ejecta dust, or 138L(circle dot) if dust-obscured. Depending on assumptions, these values limit the effective temperature of a neutron star (NS) to <4-8 MK and do not exclude models, which typically are in the range 3-4 MK. For the simplest accretion model, the accretion rate for an efficiency 77 is limited to <10(-11) eta(-1) M-circle dot yr(-1), which excludes most predictions. For pulsar activity modeled by a rotating magnetic dipole in vacuum, the limit on the magnetic field strength (B) for a given spin period (P) is B less than or similar to 10(14) P-2 G s(-2), which firmly excludes pulsars comparable to the Crab. By combining information about radiation reprocessing and geometry, we infer that the compact object is a dust-obscured thermally emitting NS, which may appear as a region of higher-temperature ejecta dust emission.

  • 3.
    Amanullah, Rahman
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Joel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ferretti, Raphael
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadogiannakis, Seméli
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Petrushevska, Tanja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Brown, P. J.
    Cao, Y.
    Contreras, C.
    Dahle, H.
    Elias-Rosa, N.
    Fynbo, J. P. U.
    Gorosabel, J.
    Guaita, L.
    Hangard, Laura
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Howell, D. A.
    Hsiao, E. Y.
    Kankare, E.
    Kasliwal, M.
    Leloudas, G.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Mattila, S.
    Nugent, P.
    Phillips, M. M.
    Sandberg, Andreas
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Stanishev, V.
    Sullivan, M.
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Östlin, Göran
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Asadi, Saghar
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Herrero-Illana, R.
    Jensen, J. J.
    Karhunen, K.
    Lazarevic, S.
    Varenius, E.
    Santos, P.
    Sridhar, S. Seethapuram
    Wallström, S. H. J.
    Wiegert, J.
    Diversity in extinction laws of Type Ia supernovae measured between 0.2 and 2 mu m2015In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 453, no 3, p. 3300-3328Article in journal (Refereed)
    Abstract [en]

    We present ultraviolet (UV) observations of six nearby Type Ia supernovae (SNe Ia) obtained with the Hubble Space Telescope, three of which were also observed in the near-IR (NIR) with Wide-Field Camera 3. UV observations with the Swift satellite, as well as ground-based optical and NIR data provide complementary information. The combined data set covers the wavelength range 0.2-2 mu m. By also including archival data of SN 2014J, we analyse a sample spanning observed colour excesses up to E(B - V) = 1.4 mag. We study the wavelength-dependent extinction of each individual SN and find a diversity of reddening laws when characterized by the total-to-selective extinction R-V. In particular, we note that for the two SNe with E(B - V) greater than or similar to 1 mag, for which the colour excess is dominated by dust extinction, we find R-V = 1.4 +/- 0.1 and R-V = 2.8 +/- 0.1. Adding UV photometry reduces the uncertainty of fitted R-V by similar to 50 per cent allowing us to also measure R-V of individual low-extinction objects which point to a similar diversity, currently not accounted for in the analyses when SNe Ia are used for studying the expansion history of the Universe.

  • 4. Blinnikov, Sergei
    et al.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Bartunov, Oleg
    Nomoto, Ken'ichi
    Iwamoto, Koichi
    Radiation Hydrodynamics of SN 1987A. I. Global Analysis of the Light Curve for the First 4 Months2000In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 532, p. 1132-1149Article in journal (Refereed)
    Abstract [en]

    The optical/UV light curves of SN 1987A are analyzed with the multienergy group radiation hydrodynamics code STELLA. The calculated monochromatic and bolometric light curves are compared with observations shortly after shock breakout, during the early plateau, through the broad second maximum, and during the earliest phase of the radioactive tail. We have concentrated on a progenitor model calculated by Nomoto & Hashimoto and Saio, Nomoto, & Kato, which assumes that 14 Msolar of the stellar mass is ejected. Using this model, we have updated constraints on the explosion energy and the extent of mixing in the ejecta. In particular, we determine the most likely range of E/M (explosion energy over ejecta mass) and R0 (radius of the progenitor). In general, our best models have energies in the range E=(1.1+/-0.3)x1051 ergs, and the agreement is better than in earlier, flux-limited diffusion calculations for the same explosion energy. Our modeled B and V fluxes compare well with observations, while the flux in U undershoots after ~10 days by a factor of a few, presumably owing to NLTE and line transfer effects. We also compare our results with IUE observations, and a very good quantitative agreement is found for the first days, and for one IUE band (2500-3000 Å) as long as for 3 months. We point out that the V flux estimated by McNaught & Zoltowski should probably be revised to a lower value.

  • 5. Bose, Subhash
    et al.
    Dong, Subo
    Pastorello, A.
    Filippenko, Alexei V.
    Kochanek, C. S.
    Mauerhan, Jon
    Romero-Canizales, C.
    Brink, Thomas G.
    Chen, Ping
    Prieto, J. L.
    Post, R.
    Ashall, Christopher
    Grupe, Dirk
    Tomasella, L.
    Benetti, Stefano
    Shappee, B. J.
    Stanek, K. Z.
    Cai, Zheng
    Falco, E.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Mattila, Seppo
    Mutel, Robert
    Ochner, Paolo
    Pooley, David
    Stritzinger, M. D.
    Villanueva, S.
    Zheng, WeiKang
    Beswick, R. J.
    Brown, Peter J.
    Cappellaro, E.
    Davis, Scott
    Fraser, Morgan
    de Jaeger, Thomas
    Elias-Rosa, N.
    Gall, C.
    Gaudi, B. Scott
    Herczeg, Gregory J.
    Hestenes, Julia
    Holoien, T. W. -S.
    Hosseinzadeh, Griffin
    Hsiao, E. Y.
    Hu, Shaoming
    Jaejin, Shin
    Jeffers, Ben
    Koff, R. A.
    Kumar, Sahana
    Kurtenkov, Alexander
    Lau, Marie Wingyee
    Prentice, Simon
    Reynolds, T.
    Rudy, Richard J.
    Shahbandeh, Melissa
    Somero, Auni
    Stassun, Keivan G.
    Thompson, Todd A.
    Valenti, Stefano
    Woo, Jong-Hak
    Yunus, Sameen
    Gaia17biu/SN 2017egm in NGC 3191: The Closest Hydrogen-poor Superluminous Supernova to Date Is in a Normal, Massive, Metal-rich Spiral Galaxy2018In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 853, no 1, article id 57Article in journal (Refereed)
    Abstract [en]

    Hydrogen-poor superluminous supernovae (SLSNe-I) have been predominantly found in low-metallicity, star-forming dwarf galaxies. Here we identify Gaia17biu/SN 2017egm as an SLSN-I occurring in a normal spiral galaxy (NGC 3191) in terms of stellar mass (several times 10(10) M-circle dot) and metallicity (roughly solar). At redshift z = 0.031, Gaia17biu is also the lowest-redshift SLSN-I to date, and the absence of a larger population of SLSNe-I in dwarf galaxies of similar redshift suggests that metallicity is likely less important to the production of SLSNe-I than previously believed. With the smallest distance and highest apparent brightness for an SLSN-I, we are able to study Gaia17biu in unprecedented detail. Its pre-peak near-ultraviolet to optical color is similar to that of Gaia16apd and among the bluest observed for an SLSN-I, while its peak luminosity (M-g = -21 mag) is substantially lower than that of Gaia16apd. Thanks to the high signal-to-noise ratios of our spectra, we identify several new spectroscopic features that may help to probe the properties of these enigmatic explosions. We detect polarization at the similar to 0.5% level that is not strongly dependent on wavelength, suggesting a modest, global departure from spherical symmetry. In addition, we put the tightest upper limit yet on the radio luminosity of an SLSN-I with < 5.4 x 10(26) erg s(-1) Hz(-1) at 10 GHz, which is almost a factor of 40 better than previous upper limits and one of the few measured at an early stage in the evolution of an SLSN-I. This limit largely rules out an association of this SLSN-I with known populations of gamma-ray-burst-like central engines.

  • 6. Chugai, N. N.
    et al.
    Blinnikov, S. I.
    Lundqvist, P.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Type II supernovae at high redshifts.2000In: Memorie della Società Astronomica Italiana, ISSN 1824-016X, Vol. 71, p. 383-388Article in journal (Refereed)
    Abstract [en]

    A hydro code coupled with radiation transfer was applied to produce monochromatic light curves of two models of type II supernovae (SN II) simulating SN II-P and SN IIb (SN 1993J-like). The authors then used these template light curves to evaluate the possibility of detecting SNe II at different redshifts. With a 5 hour exposure at VLT/FORS the SN II-P model may be detected at z = 1. However, since the model of SN II-P is underluminous at early phase (t < 10 days) by ≍1.5 mag a detection at z = 2 is quiet plausible. SN IIb can be detected as far as at z = 4. For 100% detection efficiency up to z = 2 one expects to find roughly 1 SN II yr-1arcmin-2.

  • 7. Chugai, N. N.
    et al.
    Chevalier, R. A.
    Lundqvist, P.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Circumstellar interaction of the type Ia supernova 2002ic2004In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 355, p. 627-637Article in journal (Refereed)
    Abstract [en]

    We propose a model to account for the bolometric light curve, the quasi-continuum and the CaII emission features of the peculiar type Ia supernova (SN) 2002ic, which exploded in a dense circumstellar envelope. The model suggests that the SN Ia had the maximum possible kinetic energy and that the ejecta expand in an approximately spherically symmetric (possibly clumpy) circumstellar environment. The CaII and the quasi-continuum are emitted by shocked SN ejecta that underwent deformation and fragmentation in the intershock layer. Modelling of the CaII triplet implies that the contribution of the OI 8446-Åline is about 25 per cent of the 8500-Åfeature on day 234, which permits us to recover the flux in the CaII 8579-Åtriplet from the flux of 8500-Åblend reported by Deng et al. We use the CaII doublet and triplet fluxes on day 234 to derive the electron temperature (~ 4400 K) in the CaII line-emitting zone and the ratio of the total area of dense fragments to the area of the shell, S/S0~ 102. We argue that CaII bands and the quasi-continuum originate from different zones of the shocked ejecta that reflect the abundance stratification of the supernova.

  • 8. Chugai, Nikolai N.
    et al.
    Blinnikov, Sergei I.
    Cumming, Robert J.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Bragaglia, Angela
    Filippenko, Alexei V.
    Leonard, Douglas C.
    Matheson, Thomas
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy.
    The Type IIn supernova 1994W: evidence for the explosive ejection of a circumstellar envelope2004In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 352, p. 1213-1231Article in journal (Refereed)
    Abstract [en]

    We present and analyse spectra of the Type IIn supernova (SN) 1994W obtained between 18 and 203d after explosion. During the luminous phase (first 100d) the line profiles are composed of three major components: (i) narrow P-Cygni lines with the absorption minima at -700kms-1 (ii) broad emission lines with blue velocity at zero intensity ~4000km s-1 and (iii) broad, smooth wings extending out to at least ~5000kms-1, most apparent in Hα. These components are identified with an expanding circumstellar (CS) envelope, shocked cool gas in the forward post-shock region, and multiple Thomson scattering in the CS envelope, respectively. The absence of broad P-Cygni lines from the SN is the result of the formation of an optically thick, cool, dense shell at the interface of the ejecta and the CS envelope. Models of the SN deceleration and Thomson scattering wings are used to recover the density (n~ 109cm-3), radial extent [~(4-5) × 1015cm] and Thomson optical depth (τT>~ 2.5) of the CS envelope during the first month. The plateau-like SN light curve is reproduced by a hydrodynamical model and is found to be powered by a combination of internal energy leakage after the explosion of an extended pre-SN (~1015cm) and subsequent luminosity from CS interaction. The pre-explosion kinematics of the CS envelope is recovered, and is close to homologous expansion with outer velocity ~1100kms-1 and a kinematic age of ~1.5yr. The high mass (~0.4Msolar) and kinetic energy (~2 × 1048erg) of the CS envelope, combined with low age, strongly suggest that the CS envelope was explosively ejected ~1.5yr prior to the SN explosion.

  • 9.
    Ferretti, Raphael
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Amanullah, Rahman
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bulla, Mattia
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Joel
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    No evidence of circumstellar gas surrounding Type Ia Supernova SN 2017cbvIn: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213Article in journal (Refereed)
  • 10.
    Ferretti, Raphael
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Amanullah, Rahman
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bulla, Mattia
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Joel
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    No Evidence of Circumstellar Gas Surrounding Type Ia Supernova SN 2017cbv2017In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 851, no 2, article id L43Article in journal (Refereed)
    Abstract [en]

    Nearby type Ia supernovae (SNe Ia), such as SN 2017cbv, are useful events to address the question of what the elusive progenitor systems of the explosions are. Hosseinzadeh et al. suggested that the early blue excess of the light curve of SN 2017cbv could be due to the supernova ejecta interacting with a non-degenerate companion star. Some SN Ia progenitor models suggest the existence of circumstellar (CS) environments in which strong outflows create low-density cavities of different radii. Matter deposited at the edges of the cavities should be at distances at which photoionization due to early ultraviolet (UV) radiation of SNe. Ia causes detectable changes to the observable Na I D and Ca II H&K absorption lines. To study possible narrow absorption lines from such material, we obtained a time series of high-resolution spectra of SN 2017cbv at phases between -14.8 and +83 days with respect to B-band maximum, covering the time at which photoionization is predicted to occur. Both narrow Na I D and Ca II H&K are detected in all spectra, with no measurable changes between the epochs. We use photoionization models to rule out the presence of Na I and Ca II gas clouds along the line of sight of SN 2017cbv between similar to 8 x 10(16)-2 x 10(19) cm and similar to 10(15)-10(17) cm, respectively. Assuming typical abundances, the mass of a homogeneous spherical CS gas shell with radius R must be limited to M-HI(CSM) < 3 x 10(-4) x (R/10(17)[cm(2)]) M-circle dot. The bounds point to progenitor models that deposit little gas in their CS environment.

  • 11. France, Kevin
    et al.
    McCray, Richard
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy.
    Larsson, Josefin
    Frank, Kari A.
    Burrows, David N.
    Challis, Peter
    Kirshner, Robert P.
    Chevalier, Roger A.
    Garnavich, Peter
    Heng, Kevin
    Lawrence, Stephen S.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Smith, Nathan
    Sonneborn, George
    MAPPING HIGH-VELOCITY H alpha AND Ly alpha EMISSION FROM SUPERNOVA 1987A2015In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 801, no 1, article id L16Article in journal (Refereed)
    Abstract [en]

    We present new Hubble Space Telescope images of high-velocity H alpha and Ly alpha emission in the outer debris of SN 1987 A. The Ha images are dominated by emission from hydrogen atoms crossing the reverse shock (RS). For the first time we observe emission from the RS surface well above and below the equatorial. ring (ER), suggesting a bipolar or conical structure perpendicular to the ring plane. Using the H alpha imaging, we measure the mass flux of hydrogen atoms crossing the RS front, in the velocity intervals (-7500 < V-obs < -2800 km s(-1)) and (1000 < V-obs < 7500 km s(-1)), (M)(H) over dot = 1.2 x 10(-3) M-circle dot yr(-1). We also present the first Ly alpha imaging of the whole remnant and new Chandra X-ray observations. Comparing the spatial distribution of the Ly alpha and X-ray emission, we observe that the majority of the high-velocity Ly alpha emission originates interior to the ER. The observed Ly alpha/H alpha photon ratio, < R(L alpha/H alpha)> approximate to 17, is significantly higher than the theoretically predicted ratio of approximate to 5 for neutral atoms crossing the RS front. We attribute this excess to Ly alpha emission produced by X-ray heating of the outer debris. The spatial orientation of the Ly alpha and X-ray emission suggests that X-ray heating of the outer debris is the dominant Ly alpha production mechanism in SN 1987 A at this phase in its evolution.

  • 12. France, Kevin
    et al.
    McCray, Richard
    Penton, Steven V.
    Kirshner, Robert P.
    Challis, Peter
    Laming, J. Martin
    Bouchet, Patrice
    Chevalier, Roger
    Garnavich, Peter M.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Heng, Kevin
    Larsson, Josefin
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lawrence, Stephen
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Panagia, Nino
    Pun, Chun S. J.
    Smith, Nathan
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Sonneborn, George
    Sugerman, Ben
    Wheeler, J. Craig
    HST-COS Observations of Hydrogen, Helium, Carbon, and Nitrogen Emission from the SN 1987A Reverse Shock2011In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 743, no 2, p. 186-Article in journal (Refereed)
    Abstract [en]

    We present the most sensitive ultraviolet observations of Supernova 1987A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow (Δv ~ 300 km s-1) emission lines from the circumstellar ring, broad (Δv ~ 10-20 × 103 km s-1) emission lines from the reverse shock, and ultraviolet continuum emission. The high signal-to-noise ratio (>40 per resolution element) broad Lyα emission is excited by soft X-ray and EUV heating of mostly neutral gas in the circumstellar ring and outer supernova debris. The ultraviolet continuum at λ > 1350 Å can be explained by H I two-photon (2s 2 S 1/2-1s 2 S 1/2) emission from the same region. We confirm our earlier, tentative detection of N V λ1240 emission from the reverse shock and present the first detections of broad He II λ1640, C IV λ1550, and N IV] λ1486 emission lines from the reverse shock. The helium abundance in the high-velocity material is He/H = 0.14 ± 0.06. The N V/Hα line ratio requires partial ion-electron equilibration (Te /Tp ≈ 0.14-0.35). We find that the N/C abundance ratio in the gas crossing the reverse shock is significantly higher than that in the circumstellar ring, a result that may be attributed to chemical stratification in the outer envelope of the supernova progenitor. The N/C abundance may have been stratified prior to the ring expulsion, or this result may indicate continued CNO processing in the progenitor subsequent to the expulsion of the circumstellar ring. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  • 13.
    Fransson, Claes
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Challis, Peter M.
    Chevalier, Roger A.
    Filippenko, Alexei V.
    Kirshner, Robert P.
    Kozma, Cecilia
    Stockholm University, Faculty of Science, Department of Astronomy.
    Leonard, Douglas C.
    Matheson, Thomas
    Baron, E.
    Garnavich, Peter
    Jha, Saurabh
    Leibundgut, Bruno
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pun, C. S. J.
    Wang, Lifan
    Wheeler, J. Craig
    Hubble Space Telescope and Ground-based Observations of SN 1993J and SN 1998S: CNO Processing in the Progenitors2005In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 622, p. 991-1007Article in journal (Refereed)
    Abstract [en]

    Ground-based and Hubble Space Telescope observations are presented for SN 1993J and SN 1998S. SN 1998S shows strong, relatively narrow circumstellar emission lines of N III-V and C III-IV, as well as broad lines from the ejecta. Both the broad ultraviolet and optical lines in SN 1998S indicate an expansion velocity of ~7000 km s-1. The broad emission components of Lyα and Mg II are strongly asymmetrical after day 72 past the explosion and differ in shape from Hα. Different models based on dust extinction from dust in the ejecta or shock region, in combination with Hα from a circumstellar torus, are discussed. It is concluded, however, that the double-peaked line profiles are more likely to arise as a result of optical depth effects in the narrow, cool, dense shell behind the reverse shock than in a torus-like region. The ultraviolet lines of SN 1993J are broad, with a boxlike shape, coming from the ejecta and a cool, dense shell. The shapes of the lines are well fitted by a shell with inner velocity ~7000 km s-1 and outer velocity ~10,000 km s-1. For both SN 1993J and SN 1998S a strong nitrogen enrichment is found, with N/C~12.4 in SN 1993J and N/C~6.0 in SN 1998S. From a compilation of all supernovae with determined CNO ratios, we discuss the implications of these observations for the structure of the progenitors of Type II supernovae. Based in part on observations obtained with the Hubble Space Telescope, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  • 14.
    Fransson, Claes
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Larsson, Josefin
    Migotto, Katia
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Pesce, Dominic
    Challis, Peter
    Chevalier, Roger A.
    France, Kevin
    Kirshner, Robert P.
    Leibundgut, Bruno
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    McCray, Richard
    Spyromilio, Jason
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jerkstrand, Anders
    Mattila, Seppo
    Smith, Nathan
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Wheeler, J. Craig
    Crotts, Arlin
    Garnavich, Peter
    Heng, Kevin
    Lawrence, Stephen S.
    Panagia, Nino
    Pun, Chun S. J.
    Sonneborn, George
    Sugerman, Ben
    THE DESTRUCTION OF THE CIRCUMSTELLAR RING OF SN 1987A2015In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 806, no 1, article id L19Article in journal (Refereed)
    Abstract [en]

    We present imaging and spectroscopic observations with Hubble Space Telescope and Very Large Telescope of the ring of SN 1987A from 1994 to 2014. After an almost exponential increase of the shocked emission from the hotspots up to day similar to 8000 (similar to 2009), both this and the unshocked emission are now fading. From the radial positions of the hotspots we see an acceleration of these up to 500-1000 km s(-1), consistent with the highest spectroscopic shock velocities from the radiative shocks. In the most recent observations (2013 and 2014), we find several new hotspots outside the inner ring, excited by either X-rays from the shocks or by direct shock interaction. All of these observations indicate that the interaction with the supernova ejecta is now gradually dissolving the hotspots. We predict, based on the observed decay, that the inner ring will be destroyed by similar to 2025.

  • 15.
    Fransson, Claes
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Larsson, Josefin
    Spyromilio, Jason
    Chevalier, Roger
    Gröningsson, Per
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jerkstrand, Anders
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Leibundgut, Bruno
    McCray, Richard
    Challis, Peter
    Kirshner, Robert P.
    Kjaer, Karina
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    LATE SPECTRAL EVOLUTION OF THE EJECTA AND REVERSE SHOCK IN SN 1987A2013In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 768, no 1, p. 88-Article in journal (Refereed)
    Abstract [en]

    We present observations with the Very Large Telescope and Hubble Space Telescope (HST) of the broad emission lines from the inner ejecta and reverse shock of SN 1987A from 1999 February until 2012 January (days 4381-9100 after explosion). We detect broad lines from H alpha, H beta, Mg I], Na I, [O I], [Ca II], and a feature at similar to 9220 angstrom. We identify the latter line with Mg II lambda lambda 9218, 9244, which is most likely pumped by Ly alpha fluorescence. H alpha and H beta both have a centrally peaked component extending to similar to 4500 km s(-1) and a very broad component extending to greater than or similar to 11,000 km s(-1), while the other lines have only the central component. The low-velocity component comes from unshocked ejecta, heated mainly by X-rays from the circumstellar environment, whereas the very broad component comes from faster ejecta passing through the reverse shock, created by the collision with the circumstellar ring. The flux in H alpha from the reverse shock has increased by a factor of four to six from 2000 to 2007. After that there is a tendency of flattening of the light curve, similar to what may be seen in the optical lines from the shocked ring. The core component seen in H alpha, [Ca II], and Mg II has experienced a similar increase, which is consistent with that found from HST photometry. The energy deposition of the external X-rays is calculated using explosion models for SN 1987A and we predict that the outer parts of the unshocked ejecta will continue to brighten because of this. The external X-ray illumination also explains the edge-brightened morphology of the ejecta seen in the HST images. We finally discuss evidence for dust in the ejecta from line asymmetries.

  • 16. Gerardy, Christopher L.
    et al.
    Meikle, Peter
    Kotak, Rubina
    Höflich, Peter
    Farrah, Duncan
    Filippenko, Alexei V.
    Foley, Ryan J.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mattila, Seppo
    Pozzo, Monica
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy.
    Van Dyk, Schuyler D.
    Wheeler, J. Craig
    Signatures of Delayed Detonation, Asymmetry, and Electron Capture in the Mid-Infrared Spectra of Supernovae 2003hv and 2005df2007In: The Astrophysical Journal, Vol. 661, no 2, p. 995-1012Article in journal (Refereed)
    Abstract [en]

    We present mid-infrared (5.2-15.2 μm) spectra of the Type Ia supernovae (SNe Ia) 2003hv and 2005df observed with the Spitzer Space Telescope. These are the first observed mid-infrared spectra of thermonuclear supernovae, and show strong emission from fine-structure lines of Ni, Co, S, and Ar. The detection of Ni emission in SN 2005df 135 days after the explosion provides direct observational evidence of high-density nuclear burning forming a significant amount of stable Ni in a SN Ia. The SN 2005df Ar lines also exhibit a two-pronged emission profile, implying that the Ar emission deviates significantly from spherical symmetry. The spectrum of SN 2003hv also shows signs of asymmetry, exhibiting blueshifted [Co III], which matches the blueshift of [Fe II ] lines in nearly coeval near-infrared spectra. Finally, local thermodynamic equilibrium abundance estimates for the yield of radioactive 56Ni give M56Ni~0.5 Msolar, for SN 2003hv, but only M56Ni~0.13-0.22 Msolar for the apparently subluminous SN 2005df, supporting the notion that the luminosity of SNe Ia is primarily a function of the radioactive 56Ni yield. The observed emission-line profiles in the SN 2005df spectrum indicate a chemically stratified ejecta structure, which matches the predictions of delayed detonation (DD) models, but is entirely incompatible with current three-dimensional deflagration models. Furthermore, the degree that this layering persists to the innermost regions of the supernova is difficult to explain even in a DD scenario, where the innermost ejecta are still the product of deflagration burning. Thus, while these results are roughly consistent with a delayed detonation, it is clear that a key piece of physics is still missing from our understanding of the earliest phases of SN Ia explosions.

  • 17. Graves, Genevieve J. M.
    et al.
    Challis, Peter M.
    Chevalier, Roger A.
    Crotts, Arlin
    Filippenko, Alexei V.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy.
    Garnavich, Peter
    Kirshner, Robert P.
    Li, Weidong
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    McCray, Richard
    Panagia, Nino
    Phillips, Mark M.
    Pun, Chun J. S.
    Schmidt, Brian P.
    Sonneborn, George
    Suntzeff, Nicholas B.
    Wang, Lifan
    Wheeler, J. Craig
    Limits from the Hubble Space Telescope on a Point Source in SN 1987A2005In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 629, p. 944-959Article in journal (Refereed)
    Abstract [en]

    We observed supernova 1987A (SN 1987A) with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) in 1999 September and again with the Advanced Camera for Surveys (ACS) on the HST in 2003 November. Our spectral observations cover ultraviolet (UV) and optical wavelengths from 1140 to 10266 Å, and our imaging observations cover UV and optical wavelengths from 2900 to 9650 Å. No point source is observed in the remnant. We obtain a limiting flux of Fopt<=1.6×10-14 ergs s-1 cm-2 in the wavelength range 2900-9650 Å for any continuum emitter at the center of the supernova remnant (SNR). This corresponds to an intrinsic luminosity of Lopt<=5×1033 ergs s-1. It is likely that the SNR contains opaque dust that absorbs UV and optical emission, resulting in an attenuation of ~35% due to dust absorption in the SNR. Correcting for this level of dust absorption would increase our upper limit on the luminosity of a continuum source by a factor of 1.54. Taking into account dust absorption in the remnant, we find a limit of Lopt<=8×1033 ergs s-1. We compare this upper bound with empirical evidence from point sources in other supernova remnants and with theoretical models for possible compact sources. We show that any survivor of a possible binary system must be no more luminous than an F6 main-sequence star. Bright young pulsars such as Kes 75 or the Crab pulsar are excluded by optical and X-ray limits on SN 1987A. Other nonplerionic X-ray point sources have luminosities similar to the limits on a point source in SN 1987A; RCW 103 and Cas A are slightly brighter than the limits on SN 1987A, while Pup A is slightly fainter. Of the young pulsars known to be associated with SNRs, those with ages <=5000 yr are all too bright in X-rays to be compatible with the limits on SN 1987A. Examining theoretical models for accretion onto a compact object, we find that spherical accretion onto a neutron star is firmly ruled out and that spherical accretion onto a black hole is possible only if there is a larger amount of dust absorption in the remnant than predicted. In the case of thin-disk accretion, our flux limit requires a small disk, no larger than 1010 cm, with an accretion rate no more than 0.3 times the Eddington accretion rate. Possible ways to hide a surviving compact object include the removal of all surrounding material at early times by a photon-driven wind, a small accretion disk, or very high levels of dust absorption in the remnant. It will not be easy to improve substantially on our optical-UV limit for a point source in SN 1987A, although we can hope that a better understanding of the thermal infrared emission will provide a more complete picture of the possible energy sources at the center of SN 1987A.

  • 18.
    Gröningsson, Per
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy.
    Leibundgut, Bruno
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Challis, Peter
    Chevalier, Roger
    Spyromilio, Jason
    Time evolution of the line emission from the inner circumstellar ring of SN 1987A and its hot spots2008In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 492, no 2, p. 481-491Article in journal (Refereed)
    Abstract [en]

    We present seven epochs between October 1999 and November 2007 of high resolution VLT/UVES echelle spectra of the ejecta-ring collision of SN 1987A.
The fluxes of most of the narrow lines from the unshocked gas decreased by a factor of 2-3 during this period, consistent with the decay from the initial ionization by the shock break-out. However, [O III] in particular shows an increase up to day ~6800. This agrees with radiative shock models where the pre-shocked gas is heated by the soft X-rays from the shock. The evolution of the [O III] line ratio shows a decreasing temperature of the unshocked ring gas, consistent with a transition from a hot, low density component which was heated by the initial flash ionization to the lower temperature in the pre-ionized gas ahead of the shocks.
The line emission from the shocked gas increases rapidly as the shock sweeps up more gas. We find that the neutral and high ionization lines follow the evolution of the Balmer lines roughly, while the intermediate ionization lines evolve less rapidly. Up to day ~6800, the optical light curves have a similar evolution to that of the soft X-rays. The break between day 6500 and day 7000 for [O III] and [Ne III] is likely due to recombination to lower ionization levels. Nevertheless, the evolution of the [Fe XIV] line, as well as the lines from the lowest ionization stages, continue to follow that of the soft X-rays, as expected.
There is a clear difference in the line profiles between the low and intermediate ionization lines, and those from the coronal lines at the earlier epochs. This shows that these lines arise from regions with different physical conditions, with at least a fraction of the coronal lines coming from adiabatic shocks. At later epochs the line widths of the low ionization lines, however, increase and approach those of the high ionization lines of [ Fe X-XIV] . The H line profile can be traced up to ~500 km s-1 at the latest epoch. This is consistent with the cooling time of shocks propagating into a density of (1-4) 104 cm-3. This means that these shocks are among the highest velocity radiative shocks observed.

  • 19.
    Gröningsson, Per
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, Natalia
    Stockholm University, Faculty of Science, Department of Astronomy.
    Leibundgut, Bruno
    Spyromilio, Jason
    Chevalier, Roger A.
    Gilmozzi, Roberto
    Kjær, Karina
    Mattila, Seppo
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy.
    High resolution spectroscopy of the line emission from the inner circumstellar ring of SN 1987A and its hot spots2007Report (Other academic)
    Abstract [en]

    We discuss high resolution VLT/UVES observations (FWHM ~ 6 km/s) from October 2002 (day ~5700 past explosion) of the shock interaction of SN 1987A and its circumstellar ring. A nebular analysis of the narrow lines from the unshocked gas indicates gas densities of (1.5-5.0)E3 cm-3 and temperatures of 6.5E3-2.4E4 K. This is consistent with the thermal widths of the lines. From the shocked component we observe a large range of ionization stages from neutral lines to [Fe XIV]. From a nebular analysis we find that the density in the low ionization region is 4E6-1E7 cm-3. There is a clear difference in the high velocity extension of the low ionization lines and that of lines from [Fe X-XIV], with the latter extending up to ~ -390 km/s in the blue wing for [Fe XIV], while the low ionization lines extend to typically ~ -260 km/s. For H-alpha a faint extension up to ~ -450 km/s can be seen probably arising from a small fraction of shocked high density clumps. We discuss these observations in the context of radiative shock models, which are qualitatively consistent with the observations. A fraction of the high ionization lines may originate in gas which has yet not had time to cool down, explaining the difference in width between the low and high ionization lines. The maximum shock velocities seen in the optical lines are ~ 510 km/s. We expect the maximum width of especially the low ionization lines to increase with time.

  • 20.
    Gröningsson, Per
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, Natalia
    Stockholm University, Faculty of Science, Department of Astronomy.
    Leibundgut, Bruno
    Spyromilio, Jason
    Chevalier, Roger
    Gilmozzi, Roberto
    Kjaer, Karina
    Mattila, Seppo
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy.
    High resolution spectroscopy of the inner ring of SN 1987A2008In: Astronomy and Astrophysics, ISSN 0004-6361, Vol. 479, no 3, p. 761-777Article in journal (Refereed)
    Abstract [en]

    We discuss high resolution VLT/UVES observations (FWHM similar to 6 kms(-1)) from October 2002 (day similar to 5700 past explosion) of the shock interaction of SN 1987A and its circumstellar ring. A large number of narrow emission lines from the unshocked ring, with ion stages from neutral up to Ne V and Fe VII, have been identified. A nebular analysis of the narrow lines from the unshocked gas indicates gas densities of (similar to 1.5 - 5.0) x 10(3) cm(-3) and temperatures of similar to 6.5 x 10(3) - 2.4 x 104 K. This is consistent with the thermal widths of the lines. From the shocked component we observe a large range of ionization stages from neutral lines to [FeXIV]. From a nebular analysis we find that the density in the low ionization region is 4 x 10(6) - 10(7) cm-3. There is a clear difference in the high velocity extension of the low ionization lines and that of lines from [Fe X - XIV], with the latter extending up to similar to- 390 km s(-1) in the blue wing for [Fe XIV], while the low ionization lines extend to typically similar to- 260 km s(-1). For H alpha a faint extension up to similar to- 450 km s(-1) can be seen probably arising from a small fraction of shocked high density clumps. We discuss these observations in the context of radiative shock models, which are qualitatively consistent with the observations. A fraction of the high ionization lines may originate in gas which has yet not had time to cool, explaining the difference in width between the low and high ionization lines. The maximum shock velocities seen in the optical lines are similar to 510 km s(-1). We expect the maximum width of especially the low ionization lines to increase with time.

  • 21.
    Gröningsson, Per
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Nymark, Tanja
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, Natalia
    Stockholm University, Faculty of Science, Department of Astronomy.
    Chevalier, R.
    Leibundgut, B.
    Spyromilio, J.
    Coronal emission from the shocked circumstellar ring of SN 1987A2006In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 456, no 2, p. 581-589Article in journal (Refereed)
    Abstract [en]

    High resolution spectra with UVES/VLT of SN 1987A from December 2000 until November 2005 show a number of high ionization lines from gas with velocities of ± 350 km s-1, emerging from the shocked gas formed by the ejecta-ring collision. These include coronal lines from [Fe X], [Fe XI] and [Fe XIV] which have increased by a factor of 20 during the observed period. The evolution of the lines is similar to that of the soft X-rays, indicating that they arise in the same component. The line ratios are consistent with those expected from radiative shocks with velocity 310{-}390 km s-1, corresponding to a shock temperature of (1.6{-}2.5)× 106 K. A fraction of the coronal emission may, however, originate in higher velocity adiabatic shocks.

  • 22. Heng, Kevin
    et al.
    McCray, Richard
    Zhekov, Svetozar A.
    Challis, Peter M.
    Chevalier, Roger A.
    Crotts, Arlin P. S.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy.
    Garnavich, Peter
    Kirshner, Robert P.
    Lawrence, Stephen S.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Panagia, Nino
    Pun, C. S. J.
    Smith, Nathan
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy.
    Wang, Lifan
    Evolution of the Reverse Shock Emission from SNR 1987A2006In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 644, p. 959-970Article in journal (Refereed)
    Abstract [en]

    We present new (2004 July) G750L and G140L Space Telescope Imaging Spectrograph (STIS) data of the Hα and Lyα emission from supernova remnant (SNR) 1987A. With the aid of earlier data, from 1997 October to 2002 October, we track the local evolution of Lyα emission and both the local and global evolution of Hα emission. The most recent observations allow us to directly compare the Hα and Lyα emission from the same slit position and at the same epoch. Consequently, we find clear evidence that, unlike Hα, Lyα is reflected from the debris by resonant scattering. In addition to emission that we can clearly attribute to the surface of the reverse shock, we also measure comparable emission, in both Hα and Lyα, that appears to emerge from supernova debris interior to the surface. New observations taken through slits positioned slightly eastward and westward of a central slit show a departure from cylindrical symmetry in the Hα surface emission. Using a combination of old and new observations, we construct a light curve of the total Hα flux, F, from the reverse shock, which has increased by a factor of ~4 over about 8 yr. However, due to large systematic uncertainties, we are unable to discern between the two limiting behaviors of the flux: F~t (self-similar expansion) and F~t5 (halting of the reverse shock). Such a determination is important for constraining the rate of hydrogen atoms crossing the shock, which is relevant to the question of whether the reverse shock emission will vanish in <~7 yr. Future deep, low- or moderate-resolution spectra are essential for accomplishing this task.

  • 23. Hugues, John P.
    et al.
    Chugai, Nikolai
    Chevalier, Roger
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Schlegel, Eric
    Chandra Observations of Type Ia Supernovae: Upper Limits to the X-Ray Flux of SN 2002bo, SN 2002ic, SN 2005gj, and SN 2005ke2007In: The Astrophysical Journal, Vol. 670, no 2, p. 1260-1274Article in journal (Refereed)
    Abstract [en]

    We set sensitive upper limits to the X-ray emission of four Type Ia supernovae (SNe Ia) using the Chandra X-Ray Observatory. SN 2002bo, a normal, although reddened, nearby SN Ia, was observed 9.3 days after explosion. For an absorbed, high-temperature bremsstrahlung model the flux limits are 3.2×10-16 ergs cm-2 s-1 (0.5-2 keV band) and 4.1×10-15 ergs cm-2 s-1 (2-10 keV band). Using conservative model assumptions and a 10 km s-1 wind speed, we derive a mass-loss rate of M˙~2×10-5 Msolar yr-1, which is comparable to limits set by the nondetection of Hα lines from other SNe Ia. Two other objects, SN 2002ic and SN 2005gj, observed 260 and 80 days after explosion, respectively, are the only SNe Ia showing evidence for circumstellar interaction. The SN 2002ic X-ray flux upper limits are ~4 times below predictions of the interaction model currently favored to explain the bright optical emission. To resolve this discrepancy, we invoke the mixing of cool dense ejecta fragments into the forward shock region, which produces increased X-ray absorption. A modest amount of mixing allows us to accommodate the Chandra upper limit. SN 2005gj is less well studied at this time. Assuming the same circumstellar environment as for SN 2002ic, the X-ray flux upper limits for SN 2005gj are ~4 times below the predictions, suggesting that mixing of cool ejecta into the forward shock has also occurred here. Our reanalysis of Swift and Chandra data on SN 2005ke does not confirm a previously reported X-ray detection. The host galaxies NGC 3190 (SN 2002bo) and NGC 1371 (SN 2005ke) each harbor a low-luminosity [LX~(3-4)×1040 ergs s-1] active nucleus in addition to widespread diffuse soft X-ray emission.

  • 24. Indebetouw, R.
    et al.
    Matsuura, M.
    Dwek, E.
    Zanardo, G.
    Barlow, M. J.
    Baes, M.
    Bouchet, P.
    Burrows, D. N.
    Chevalier, R.
    Clayton, G. C.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Gaensler, B.
    Kirshner, R.
    Lakicevic, M.
    Long, K. S.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Marti-Vidal, I.
    Marcaide, J.
    McCray, R.
    Meixner, M.
    Ng, C. -Y
    Park, S.
    Sonneborn, G.
    Staveley-Smith, L.
    Vlahakis, C.
    van Loon, J.
    DUST PRODUCTION AND PARTICLE ACCELERATION IN SUPERNOVA 1987A REVEALED WITH ALMA2014In: The Astrophysical Journal Letters, ISSN 2041-8205, Vol. 782, no 1, p. L2-Article in journal (Refereed)
    Abstract [en]

    Supernova (SN) explosions are crucial engines driving the evolution of galaxies by shock heating gas, increasing the metallicity, creating dust, and accelerating energetic particles. In 2012 we used the Atacama Large Millimeter/Submillimeter Array to observe SN 1987A, one of the best-observed supernovae since the invention of the telescope. We present spatially resolved images at 450 mu m, 870 mu m, 1.4 mm, and 2.8 mm, an important transition wavelength range. Longer wavelength emission is dominated by synchrotron radiation from shock-accelerated particles, shorter wavelengths by emission from the largest mass of dust measured in a supernova remnant (>0.2 M-circle dot). For the first time we show unambiguously that this dust has formed in the inner ejecta (the cold remnants of the exploded star's core). The dust emission is concentrated at the center of the remnant, so the dust has not yet been affected by the shocks. If a significant fraction survives, and if SN 1987A is typical, supernovae are important cosmological dust producers.

  • 25. Iping, Rosina C.
    et al.
    Sonneborn, George
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Search for O VI Emission from the Shocked Circumstellar Ring of SN 1987A2007In: SUPERNOVA 1987A: 20 YEARS AFTER: Supernovae and Gamma-Ray Bursters, 2007, p. 182-184Conference paper (Other academic)
    Abstract [en]

    A search for O VI 1032-38 Å emission from the circumstellar shock interaction zones of SN 1987A was made with the FUSE satellite. The shock interaction of supernova ejecta with the dense inner ring began in the mid-1990s. Broad (FWHM ~300 km s−1) emission from optical coronal lines (e.g. [Fe X], [Fe XI], and [Fe XIV]) has emerged and increased exponentially in strength. O VI emission is expected to track the coronal lines and is expected to be the primary cooling transition for the million-degree shocked gas. In the most recent FUSE observation of SN 1987A, June 2004, a weak broad O VI feature may be present. An upper limit on the intrinsic O VI flux is ~1×10−13 erg cm−2 s−1 (corrected for foreground Galactic and LMC extinction). A follow-up observation of planned for mid-2007.

  • 26. Kangas, T.
    et al.
    Blagorodnova, N.
    Mattila, S.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Fraser, M.
    Burgaz, U.
    Cappellaro, E.
    Martínez, J. M. Carrasco
    Elias-Rosa, N.
    Hardy, L. K.
    Harmanen, J.
    Hsiao, E. Y.
    Isern, J.
    Kankare, E.
    Kołaczkowski, Z.
    Nielsen, M. B.
    Reynolds, T. M.
    Rhodes, L.
    Somero, A.
    Stritzinger, M. D.
    Wyrzykowski, Ł.
    Gaia16apd-a link between fast and slowly declining type I superluminous supernovae2017In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 469, no 1, p. 1246-1258Article in journal (Refereed)
    Abstract [en]

    We present ultraviolet (UV), optical and infrared photometry and optical spectroscopy of the type Ic superluminous supernova (SLSN) Gaia16apd (= SN 2016eay), covering its evolution from 26 d before the g-band peak to 234.1 d after the peak. Gaia16apd was followed as a part of the NOT Unbiased Transient Survey (NUTS). It is one of the closest SLSNe known (z = 0.102 +/- 0.001), with detailed optical and UV observations covering the peak. Gaia16apd is a spectroscopically typical type Ic SLSN, exhibiting the characteristic blue early spectra with O II absorption, and reaches a peak M-g = -21.8 +/- 0.1 mag. However, photometrically it exhibits an evolution intermediate between the fast and slowly declining type Ic SLSNe, with an early evolution closer to the fast-declining events. Together with LSQ12dlf, another SLSN with similar properties, it demonstrates a possible continuum between fast and slowly declining events. It is unusually UV-bright even for an SLSN, reaching a non-K-corrected M-uvm2 similar or equal to -23.3 mag, the only other type Ic SLSN with similar UV brightness being SN 2010gx. Assuming that Gaia16apd was powered by magnetar spin-down, we derive a period of P = 1.9 +/- 0.2 ms and a magnetic field of B = 1.9 +/- 0.2 x 10(14) G for the magnetar. The estimated ejecta mass is between 8 and 16 M circle dot, and the kinetic energy between 1.3 and 2.5 x 10(52) erg, depending on opacity and assuming that the entire ejecta is swept up into a thin shell. Despite the early photometric differences, the spectra at late times are similar to slowly declining type Ic SLSNe, implying that the two subclasses originate from similar progenitors.

  • 27. Kangas, T.
    et al.
    Mattila, S.
    Kankare, E.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Vaeisaenen, P.
    Childress, M.
    Pignata, G.
    McCully, C.
    Valenti, S.
    Vinko, J.
    Pastorello, A.
    Elias-Rosa, N.
    Fraser, M.
    Gal-Yam, A.
    Kotak, R.
    Kotilainen, J. K.
    Smartt, S. J.
    Galbany, L.
    Harmanen, J.
    Howell, D. A.
    Inserra, C.
    Marion, G. H.
    Quimby, R. M.
    Silverman, J. M.
    Szalai, T.
    Wheeler, J. C.
    Ashall, C.
    Benetti, S.
    Romero-Canizales, C.
    Smith, K. W.
    Sullivan, M.
    Takats, K.
    Young, D. R.
    Supernova 2013fc in a circumnuclear ring of a luminous infrared galaxy: the big brother of SN 1998S2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 456, no 1, p. 323-346Article in journal (Refereed)
    Abstract [en]

    We present photometric and spectroscopic observations of SN 2013fc, a bright type II supernova (SN) in a circumnuclear star-forming ring in the luminous infrared galaxy ESO 154-G010, observed as part of the Public ESO Spectroscopic Survey of Transient Objects. SN 2013fc is both photometrically and spectroscopically similar to the well-studied type IIn SN 1998S and to the bright type II-L SN 1979C. It exhibits an initial linear decline, followed by a short plateau phase and a tail phase with a decline too fast for Co-56 decay with full. gamma-ray trapping. Initially, the spectrum was blue and featureless. Later on, a strong broad (similar to 8000 km s(-1)) H alpha emission profile became prominent. We apply a STARLIGHT stellar population model fit to the SN location (observed when the SN had faded) to estimate a high extinction of A(V) = 2.9 +/- 0.2 mag and an age of 10(+ 3) (- 2) Myr for the underlying cluster. We compare the SN to SNe 1998S and 1979C and discuss its possible progenitor star considering the similarities to these events. With a peak brightness of B = - 20.46 +/- 0.21 mag, SN 2013fc is 0.9 mag brighter than SN 1998S and of comparable brightness to SN 1979C. We suggest that SN 2013fc was consistent with a massive red supergiant (RSG) progenitor. Recent mass loss probably due to a strong RSG wind created the circumstellar matter illuminated through its interaction with the SN ejecta. We also observe a near- infrared excess, possibly due to newly condensed dust.

  • 28. Kankare, E.
    et al.
    Ergon, Mattias
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bufano, F.
    Spyromilio, J.
    Mattila, S.
    Chugai, N. N.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Pastorello, A.
    Kotak, R.
    Benetti, S.
    Botticella, M. -T
    Cumming, R. J.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Fraser, M.
    Leloudas, Georgios
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Miluzio, M.
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Stritzinger, M.
    Turatto, M.
    Valenti, S.
    SN 2009kn-the twin of the Type IIn supernova 1994W2012In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 424, no 2, p. 855-873Article in journal (Refereed)
    Abstract [en]

    We present an optical and near-infrared photometric and spectroscopic study of supernova (SN) 2009kn spanning similar to 1.5 yr from the discovery. The optical spectra are dominated by the narrow (full width at half-maximum similar to 1000 km s-1) Balmer lines distinctive of a Type IIn SN with P Cygni profiles. Contrarily, the photometric evolution resembles more that of a Type IIP SN with a large drop in luminosity at the end of the plateau phase. These characteristics are similar to those of SN 1994W, whose nature has been explained with two different models with different approaches. The well-sampled data set on SN 2009kn offers the possibility to test these models, in the case of both SN 2009kn and SN 1994W. We associate the narrow P Cygni lines with a swept-up shell composed of circumstellar matter and SN ejecta. The broad emission line wings, seen during the plateau phase, arise from internal electron scattering in this shell. The slope of the light curve after the post-plateau drop is fairly consistent with that expected from the radioactive decay of 56Co, suggesting an SN origin for SN 2009kn. Assuming radioactivity to be the main source powering the light curve of SN 2009kn in the tail phase, we infer an upper limit for 56Ni mass of 0.023 M?. This is significantly higher than that estimated for SN 1994W, which also showed a much steeper decline of the light curve after the post-plateau drop. We also observe late-time near-infrared emission which most likely arises from newly formed dust produced by SN 2009kn. As with SN 1994W, no broad lines are observed in the spectra of SN 2009kn, not even in the late-time tail phase.

  • 29. Kankare, E.
    et al.
    Kotak, R.
    Mattila, S.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ward, M. J.
    Fraser, M.
    Lawrence, A.
    Smartt, S. J.
    Meikle, W. P. S.
    Bruce, A.
    Harmanen, J.
    Hutton, S. J.
    Inserra, C.
    Kangas, T.
    Pastorello, A.
    Reynolds, T.
    Romero-Canizales, C.
    Smith, K. W.
    Valenti, S.
    Chambers, K. C.
    Hodapp, K. W.
    Huber, M. E.
    Kaiser, N.
    Kudritzki, R. -P.
    Magnier, E. A.
    Tonry, J. L.
    Wainscoat, R. J.
    Waters, C.
    A population of highly energetic transient events in the centres of active galaxies2017In: Nature Astronomy, ISSN 2397-3366, Vol. 1, no 12, p. 865-871Article in journal (Refereed)
    Abstract [en]

    Recent all-sky surveys have led to the discovery of new types of transients. These include stars disrupted by the central supermassive black hole, and supernovae that are 10-100 times more energetic than typical ones. However, the nature of even more energetic transients that apparently occur in the innermost regions of their host galaxies is hotly debated1-3. Here we report the discovery of the most energetic of these to date: PS1-10adi, with a total radiated energy of similar to 2.3 x 10(52) erg. The slow evolution of its light curve and persistently narrow spectral lines over similar to 3 yr are inconsistent with known types of recurring black hole variability. The observed properties imply powering by shock interaction between expanding material and large quantities of surrounding dense matter. Plausible sources of this expanding material are a star that has been tidally disrupted by the central black hole, or a supernova. Both could satisfy the energy budget. For the former, we would be forced to invoke a new and hitherto unseen variant of a tidally disrupted star, while a supernova origin relies principally on environmental effects resulting from its nuclear location. Remarkably, we also discover that PS1-10adi is not an isolated case. We therefore surmise that this new population of transients has previously been overlooked due to incorrect association with underlying central black hole activity.

  • 30. Kosenko, D. I.
    et al.
    Blinnikov, S. I.
    Postnov, K. A.
    Lundqvist, P.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Sorokina, E. I.
    Time-dependent thermal X-ray afterglows from GRBS2004In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 34, p. 2705-2710Article in journal (Refereed)
    Abstract [en]

    Time-dependent thermal X-ray spectra are calculated from physically plausible conditions around GRB. It is shown that account for time-dependent ionization processes strongly affects the observed spectra of hot rarefied plasma. These calculations may provide an alternative explanation to the observed X-ray lines of early GRBs afterglows (such as GRB 011211). Our technique will allow one to obtain independent constraints on the GRB collimation angle and on the clumpiness of circumstellar matter.

  • 31. Kosenko, D. I.
    et al.
    Sorokina, E. I.
    Blinnikov, S. I.
    Lundqvist, P.
    Stockholm University, Faculty of Science, Department of Astronomy.
    X-ray emission of young SN Ia remnants as a probe for an explosion model2004In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 33, p. 392-397Article in journal (Refereed)
    Abstract [en]

    We present results of hydrodynamical simulations of young supernova remnants. To model the ejecta, we use several models (discussed in the literature) of type Ia supernova explosions with different abundances. Our hydro models are one-dimensional and spherically symmetrical, but they take into account ionization kinetics with all important processes. We include detailed calculations for the X-ray emission, allowing for time-dependent ionization and recombination. In particular, we compare the computed X-ray spectra with recent XMM-Newton observations of the Tycho supernova remnant (SNR). Our goal is to find the most viable thermonuclear SN model that gives good fits to both these X-ray observations and typical SN Ia light curves.

  • 32. Kotak, R.
    et al.
    Meikle, W. P. S.
    Farrah, D.
    Gerardy, C. L.
    Foley, R. J.
    Van Dyk, S. D.
    Fransson, C.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy.
    Fesen, R.
    Filippenko, A. V.
    Mattila, S.
    Silverman, J. M.
    Andersen, A. C.
    Höflich, P. A.
    Pozzo, M.
    Wheeler, J. C.
    Dust and The Type II-Plateau Supernova 2004et2009In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 704, no 1, p. 306-323Article in journal (Refereed)
    Abstract [en]

    We present mid-infrared (MIR) observations of the Type II-plateau supernova (SN) 2004et, obtained with the Spitzer Space Telescope between 64 and 1406 days past explosion. Late-time optical spectra are also presented. For the period 300-795 days past explosion, we argue that the spectral energy distribution (SED) of SN 2004et comprises (1) a hot component due to emission from optically thick gas, as well as free-bound radiation; (2) a warm component due to newly formed, radioactively heated dust in the ejecta; and (3) a cold component due to an IR echo from the interstellar-medium dust of the host galaxy, NGC 6946. There may also have been a small contribution to the IR SED due to free-free emission from ionized gas in the ejecta. We reveal the first-ever spectroscopic evidence for silicate dust formed in the ejecta of a supernova. This is supported by our detection of a large, but progressively declining, mass of SiO. However, we conclude that the mass of directly detected ejecta dust grew to no more than a few times 10-4 M sun. We also provide evidence that the ejecta dust formed in comoving clumps of fixed size. We argue that, after about two years past explosion, the appearance of wide, box-shaped optical line profiles was due to the impact of the ejecta on the progenitor circumstellar medium and that the subsequent formation of a cool, dense shell was responsible for a later rise in the MIR flux. This study demonstrates the rich, multifaceted ways in which a typical core-collapse supernova and its progenitor can produce and/or interact with dust grains. The work presented here adds to the growing number of studies that do not support the contention that SNe are responsible for the large mass of observed dust in high-redshift galaxies.

  • 33. Kotak, Rubina
    et al.
    Meikle, Peter
    Pozzo, Monica
    van Dyk, Schuyler
    Farrah, Duncan
    Fesen, Robert
    Filippenko, Alexei
    Foley, Ryan
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy.
    Gerardy, Christopher
    Höflich, Peter
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mattila, Seppo
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy.
    Wheeler, J. Craig
    Spitzer Measurements of Atomic and Molecular Abundances in the Type IIP SN 2005af2006In: The Astrophysical Journal, ISSN 0004-637X, Vol. 651, no 2, p. L117-L120Article in journal (Refereed)
    Abstract [en]

    We present results based on mid-infrared (3.6-30 μm) observations with the Spitzer Space Telescope of the nearby Type IIP supernova 2005af. We report the first ever detection of the SiO molecule in a Type IIP supernova. Together with the detection of the CO fundamental, this is an exciting finding as it may signal the onset of dust condensation in the ejecta. From a wealth of fine-structure lines we provide abundance estimates for stable Ni, Ar, and Ne that, via spectral synthesis, may be used to constrain nucleosynthesis models.

  • 34. Kuncarayakti, Hanindyo
    et al.
    Maeda, Keiichi
    Ashall, Christopher J.
    Prentice, Simon J.
    Mattila, Seppo
    Kankare, Erkki
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Pastorello, Andrea
    Leloudas, Giorgos
    Anderson, Joseph P.
    Benetti, Stefano
    Bersten, Melina C.
    Cappellaro, Enrico
    Cartier, Regis
    Denneau, Larry
    Della Valle, Massimo
    Elias-Rosa, Nancy
    Folatelli, Gaston
    Fraser, Morgan
    Galbany, Lluis
    Gall, Christa
    Gal-Yam, Avishay
    Gutierrez, Claudia P.
    Hamanowicz, Aleksandra
    Heinze, Ari
    Inserra, Cosimo
    Kangas, Tuomas
    Mazzali, Paolo
    Melandri, Andrea
    Pignata, Giuliano
    Rest, Armin
    Reynolds, Thomas
    Roy, Rupak
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Inter-University Centre for Astronomy and Astrophysics (IUCAA), India.
    Smartt, Stephen J.
    Smith, Ken W.
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Somero, Auni
    Stalder, Brian
    Stritzinger, Maximilian
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tomasella, Lina
    Tonry, John
    Weiland, Henry
    Young, David R.
    SN 2017dio: A Type-Ic Supernova Exploding in a Hydrogen-rich Circumstellar Medium2018In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 854, no 1, article id L14Article in journal (Refereed)
    Abstract [en]

    SN 2017dio shows both spectral characteristics of a type-Ic supernova (SN) and signs of a hydrogen-rich circumstellar medium (CSM). Prominent, narrow emission lines of H and He are superposed on the continuum. Subsequent evolution revealed that the SN ejecta are interacting with the CSM. The initial SN Ic identification was confirmed by removing the CSM interaction component from the spectrum and comparing with known SNe Ic and, reversely, adding a CSM interaction component to the spectra of known SNe Ic and comparing them to SN 2017dio. Excellent agreement was obtained with both procedures, reinforcing the SN Ic classification. The light curve constrains the pre-interaction SN Ic peak absolute magnitude to be around M-g = -17.6 mag. No evidence of significant extinction is found, ruling out a brighter luminosity required by an SN Ia classification. These pieces of evidence support the view that SN 2017dio is an SN Ic, and therefore the first firm case of an SN Ic with signatures of hydrogen-rich CSM in the early spectrum. The CSM is unlikely to have been shaped by steady-state stellar winds. The mass loss of the progenitor star must have been intense, M similar to 0.02 (epsilon(H alpha)/0.01)(-1) (nu(wind)/500 km s(-1)) (nu(shock)/10,000 km s(-1))M--3(circle dot) yr(-1), peaking at a few decades before the SN. Such a high mass-loss rate might have been experienced by the progenitor through eruptions or binary stripping.

  • 35.
    Kundu, Esha
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Perez-Torres, M. A.
    Herrero-Illana, R.
    Alberdi, A.
    Constraining Magnetic Field Amplification in SN Shocks Using Radio Observations of SNe 2011fe and 2014J2017In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 842, no 1, article id 17Article in journal (Refereed)
    Abstract [en]

    We modeled the radio non-detection of two Type Ia supernovae (SNe), SN 2011fe and SN 2014J, considering synchrotron emission from the interaction between SN ejecta and the circumstellar medium. For ejecta whose outer parts have a power-law density structure, we compare synchrotron emission with radio observations. Assuming that 20% of the bulk shock energy is being shared equally between electrons and magnetic fields, we found a very low-density medium around both the SNe. A less tenuous medium with particle density similar to 1 cm(-3), which could be expected around both SNe, can be estimated when the magnetic field amplification is less than that presumed for energy equipartition. This conclusion also holds if the progenitor of SN. 2014J was a rigidly rotating white dwarf (WD) with a main-sequence (MS) or red giant companion. For a He star companion, or a MS for SN. 2014J, with 10% and 1% of bulk kinetic energy in magnetic fields, we obtain mass-loss rates of < 10(-9) and <similar to 4 x10(-9)M yr(-1). for a wind velocity of 100 km s(-1). The former requires a mass accretion efficiency of > 99% onto the WD, but is less restricted for the latter case. However, if the tenuous medium is due to a recurrent nova, it is difficult from our model to predict synchrotron luminosities. Although the formation channels of SNe. 2011fe and 2014J are not clear, the null detection in radio wavelengths could point toward a low amplification efficiency for magnetic fields in SN shocks.

  • 36. Larsson, Josefin
    et al.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Kjaer, Karina
    Jerkstrand, Anders
    Kirshner, Robert P.
    Leibundgut, Bruno
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Mattila, Seppo
    McCray, Richard
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Spyromilio, Jason
    Wheeler, J. Craig
    THE MORPHOLOGY OF THE EJECTA IN SUPERNOVA 1987A: A STUDY OVER TIME AND WAVELENGTH2013In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 768, no 1, p. 89-Article in journal (Refereed)
    Abstract [en]

    We present a study of the morphology of the ejecta in Supernova 1987A based on images and spectra from the Hubble Space Telescope (HST) as well as integral field spectroscopy from VLT/SINFONI. The HST observations were obtained between 1994 and 2011 and primarily probe the outer H-rich zones of the ejecta. The SINFONI observations were obtained in 2005 and 2011 and instead probe the [Si I]+[Fe II] emission from the inner regions. We find a strong temporal evolution of the morphology in the HST images, from a roughly elliptical shape before similar to 5000 days, to a more irregular, edge-brightened morphology with a hole in the middle thereafter. This transition is a natural consequence of the change in the dominant energy source powering the ejecta, from radioactive decay before similar to 5000 days to X-ray input from the circumstellar interaction thereafter. The [Si I]+[Fe II] images display a more uniform morphology, which may be due to a remaining significant contribution from radioactivity in the inner ejecta and the higher abundance of these elements in the core. Both the Ha and the [Si I]+[Fe II] line profiles show that the ejecta are distributed fairly close to the plane of the inner circumstellar ring, which is assumed to define the rotational axis of the progenitor star. The Ha emission extends to higher velocities than [Si I]+[Fe II], as expected from theoretical models. There is no clear symmetry axis for all the emission. Instead, we find that the emission is concentrated to clumps and that the emission is distributed somewhat closer to the ring in the north than in the south. This north-south asymmetry may be partially explained by dust absorption. We compare our results with explosion models and find some qualitative agreement, but note that the observations show a higher degree of large-scale asymmetry.

  • 37. Larsson, Josefin
    et al.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Spyromilio, J.
    Leibundgut, B. .
    Challis, P.
    Chevalier, R. A.
    France, K.
    Jerkstrand, A.
    Kirshner, R. P.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Matsuura, M.
    McCray, R.
    Smith, N.
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Garnavich, P.
    Heng, K.
    Lawrence, S.
    Mattila, S.
    Migotto, Katia
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Sonneborn, G.
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Wheeler, J. C.
    THREE-DIMENSIONAL DISTRIBUTION OF EJECTA IN SUPERNOVA 1987A AT 10,000 DAYS2016In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 833, no 2, article id 147Article in journal (Refereed)
    Abstract [en]

    Due to its proximity, SN. 1987A offers a unique opportunity to directly observe the geometry of a stellar explosion as it unfolds. Here we present spectral and imaging observations of SN. 1987A obtained similar to 10,000 days after the explosion with HST/STIS and VLT/SINFONI at optical and near-infrared wavelengths. These observations allow us to produce the most detailed 3D map of Ha to date, the first 3D maps for [Ca II] lambda lambda 7292, 7324, [O I] lambda lambda 6300, 6364, and Mg. II lambda lambda 9218, 9244, as well as new maps for [Si I]+[Fe II] 1.644 mu m and He I 2.058 mu m. A comparison with previous observations shows that the [Si I]+[Fe II] flux and morphology have not changed significantly during the past ten years, providing evidence that this line is powered by Ti-44. The time evolution of Ha shows that it is predominantly powered by X-rays from the ring, in agreement with previous findings. All lines that have sufficient signal show a similar large-scale 3D structure, with a north-south asymmetry that resembles a broken dipole. This structure correlates with early observations of asymmetries, showing that there is a global asymmetry that extends from the inner core to the outer envelope. On smaller scales, the two brightest lines, Ha and [Si I]+[Fe II] 1.644 mu m, show substructures at the level of similar to 200-1000 km s(-1) and clear differences in their 3D geometries. We discuss these results in the context of explosion models and the properties of dust in the ejecta.

  • 38.
    Larsson, Josefin
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Östlin, Göran
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Gröningsson, P.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jerkstrand, Anders
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Kozma, Cecilia
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Challis, P.
    Kirshner, R. P.
    Chevalier, R. A.
    Heng, K.
    McCray, R.
    Suntzeff, N. B.
    Bouchet, P.
    Crotts, A.
    Danziger, J.
    Dwek, E.
    France, K.
    Garnavich, P. M.
    Lawrence, S. S.
    Leibundgut, B.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Panagia, N.
    Pun, C. S. J.
    Smith, N.
    Sonneborn, G.
    Wang, L.
    Wheeler, J. C.
    X-ray illumination of the ejecta of supernova 1987A2011In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 474, no 7352, p. 484-486Article in journal (Refereed)
    Abstract [en]

    When a massive star explodes as a supernova, substantial amounts of radioactive elements-primarily (56)Ni, (57)Ni and (44)Ti-are produced(1). After the initial flash of light from shock heating, the fading light emitted by the supernova is due to the decay of these elements(2). However, after decades, the energy powering a supernova remnant comes from the shock interaction between the ejecta and the surrounding medium(3). The transition to this phase has hitherto not been observed: supernovae occur too infrequently in the Milky Way to provide a young example, and extragalactic supernovae are generally too faint and too small. Here we report observations that show this transition in the supernova SN 1987A in the Large Magellanic Cloud. From 1994 to 2001, the ejecta faded owing to radioactive decay of (44)Ti as predicted. Then the flux started to increase, more than doubling by the end of 2009. We show that this increase is the result of heat deposited by X-rays produced as the ejecta interacts with the surrounding material. In time, the X-rays will penetrate farther into the ejecta, enabling us to analyse the structure and chemistry of the vanished star.

  • 39.
    Lee, Kai-Yan
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Mellema, Garrelt
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Efficient photoheating algorithms in time-dependent photoionization simulations2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 455, no 4, p. 4406-4425Article in journal (Refereed)
    Abstract [en]

    We present an extension to the time-dependent photoionization code C-2-RAY to calculate photoheating in an efficient and accurate way. In C-2-RAY, the thermal calculation demands relatively small time-steps for accurate results. We describe two novel methods to reduce the computational cost associated with small time-steps, namely, an adaptive time-step algorithm and an asynchronous evolution approach. The adaptive time-step algorithm determines an optimal time-step for the next computational step. It uses a fast ray-tracing scheme to quickly locate the relevant cells for this determination and only use these cells for the calculation of the time-step. Asynchronous evolution allows different cells to evolve with different time-steps. The asynchronized clocks of the cells are synchronized at the times where outputs are produced. By only evolving cells which may require short time-steps with these short time-steps instead of imposing them to the whole grid, the computational cost of the calculation can be substantially reduced. We show that our methods work well for several cosmologically relevant test problems and validate our results by comparing to the results of another time-dependent photoionization code.

  • 40.
    Lundqvist, Natalia
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Björnsson, Claes-Ingvar
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pires, S.
    Shibanov, Yu. A.
    Zyuzin, D. A.
    Spectral evolution and polarization of variable structures in the pulsar wind nebula of PSR B0540-69.32011In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 413, no 1, p. 611-627Article in journal (Refereed)
    Abstract [en]

    We present high spatial resolution optical imaging and polarization observations of the PSR B0540-69.3 and its highly dynamical pulsar wind nebula (PWN) performed with Hubble Space Telescope, and compare them with X-ray data obtained with the Chandra X-ray Observatory. In particular, we have studied the bright region south-west of the pulsar where a bright 'blob' is seen in 1999. In a recent paper by De Luca et al. it was argued that the 'blob' moves away from the pulsar at high speed. We show that it may instead be a result of local energy deposition around 1999, and that the emission from this then faded away rather than moved outward. Polarization data from 2007 show that the polarization properties show dramatic spatial variations at the 1999 blob position arguing for a local process. Several other positions along the pulsar-'blob' orientation show similar changes in polarization, indicating previous recent local energy depositions. In X-rays, the spectrum steepens away from the 'blob' position, faster orthogonal to the pulsar-'blob' direction than along this axis of orientation. This could indicate that the pulsar-'blob' orientation is an axis along where energy in the PWN is mainly injected, and that this is then mediated to the filaments in the PWN by shocks. We highlight this by constructing an [S ii]-to-[O iii]-ratio map, and comparing this to optical continuum and X-ray emission maps. We argue, through modelling, that the high [S ii]/[O iii] ratio is not due to time-dependent photoionization caused by possible rapid X-ray emission variations in the 'blob' region. We have also created a multiwavelength energy spectrum for the 'blob' position showing that one can, to within 2 Sigma, connect the optical and X-ray emission by a single power law. The slope of that power law (defined from <file name=mnr_18159_mu1.gif type=gif/>) would be alpha(nu) = 0.74 +/- 0.03, which is marginally different from the X-ray spectral slope alone with alpha(nu) = 0.65 +/- 0.03. A single power law for most of the PWN is, however, not be possible. We obtain best power-law fits for the X-ray spectrum if we include 'extra' oxygen, in addition to the oxygen column density in the interstellar gas of the Large Magellanic Cloud and the Milky Way. This oxygen is most naturally explained by the oxygen-rich ejecta of the supernova remnant. The oxygen needed likely places the progenitor mass in the 20-25 M(circle dot) range, i.e. in the upper mass range for progenitors of Type IIP supernovae.

  • 41.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    The Flash Ionization of the Circumstellar Gas of SN 1987A2007In: UPERNOVA 1987A: 20 YEARS AFTER: Supernovae and Gamma-Ray Bursters, 2007Conference paper (Other academic)
    Abstract [en]

    The photons from the shock breakout of SN 1987A ionized the gas they encountered in less than a few hours. Twenty years later the recombining circumstellar gas is still glowing. Here we discuss what the analysis of this emission has revealed about the structure and properties of the circumstellar gas, as well as about the properties of the shock breakout.

  • 42.
    Lundqvist, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Mattila, Seppo
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Kozma, Cecilia
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Baron, E.
    Cox, Nick L. J.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Leibundgut, Bruno
    Spyromilio, Jason
    Hydrogen and helium in the spectra of Type Ia supernovae2013In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 435, no 1, p. 329-345Article in journal (Refereed)
    Abstract [en]

    We present predictions for hydrogen and helium emission line luminosities from circumstellar matter around Type Ia supernovae (SNe Ia) using time dependent photoionization modelling. Early high-resolution ESO/Very Large Telescope (VLT) optical echelle spectra of the SN Ia 2000cx were taken before and up to similar to 70 d after maximum to probe the existence of such narrow emission lines from the supernova. We detect no such lines, and from our modelling place an upper limit on the mass-loss rate for the putative wind from the progenitor system,. M less than or similar to 1.3 x 10(-5) M-circle dot yr(-1), assuming a speed of 10 km s(-1) and solar abundances for the wind. If the wind would be helium-enriched and/or faster, the upper limit on. M could be significantly higher. In the helium-enriched case, we show that the best line to constrain the mass-loss would be He I.10 830. In addition to confirming the details of interstellar Na I and Ca II absorption towards SN 2000cx as discussed by Patat et al., we also find evidence for 6613.56 angstrom diffuse interstellar band absorption in the Milky Way. We also discuss measurements of the X-ray emission from the interaction between the supernova ejecta and the wind and we re-evaluate observations of SN 1992A obtained similar to 16 d after maximum by Schlegel & Petre. We find an upper limit of. M less than or similar to 1.3 x 10(-5) M-circle dot yr(-1) which is significantly higher than that estimated by Schlegel & Petre. These results, together with the previous observational work on the normal SNe Ia 1994D and 2001el, disfavour a symbiotic star in the upper mass-loss rate regime (so-called Mira-type systems) from being the likely progenitor scenario for these SNe. Our model calculations are general, and can also be used for the subclass of SNe Ia that do show circumstellar interaction, e. g. the recent PTF 11kx. To constrain hydrogen in late-time spectra, we present ESO/VLT and ESO/New Technology Telescope optical and infrared observations of SNe Ia 1998bu and 2000cx in the nebular phase, 251-388 d after maximum. We see no signs of hydrogen line emission in SNe 1998bu and 2000cx at these epochs, and from the absence of Ha with a width of the order of similar to 10(3) km s(-1), we argue from modelling that the mass of such hydrogen-rich gas must be less than or similar to 0.03 M circle dot for both supernovae. Comparing similar upper limits with recent models of Pan et al., it seems that hydrogen-rich donors with a separation of less than or similar to 5 times the radius of the donor may be ruled out for the five SNe Ia 1998bu, 2000cx, 2001el, 2005am and 2005cf. Larger separation, helium-rich donors, or a double-degenerate origin for these supernovae seems more likely. Our models have also been used to put the limit on hydrogen-rich gas in the recent SN 2011fe, and for this supernova, a double-degenerate origin seems likely.

  • 43.
    Lundqvist, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nyholm, Anders
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Joel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Kozma, Cecilia
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lundqvist, N.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Garnavich, P. M.
    Kromer, Marcus
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Shappee, B. J.
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    No trace of a single-degenerate companion in late spectra of supernovae 2011fe and 2014J2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 577Article in journal (Refereed)
    Abstract [en]

    Aims. This study aims at constraining the origin of the nearby Type Ia supernovae (SNe), 2011fe and 2014J. The two most favoured scenarios for triggering the explosion of the white dwarf supernova progenitor is either mass loss from a non-degenerate companion or merger with another white dwarf. In the former, there could be a significant amount of leftover material from the companion at the centre of the supernova. Detecting such material would therefore favour the single-degenerate scenario. Methods. The left-over material from a possible non-degenerate companion can reveal itself after about one year, and in this study such material was searched for in the spectra of SN 2011fe (at 294 days after the explosion) using the Large Binocular Telescope and for SN 2014J using the Nordic Optical Telescope (315 days past explosion). The observations were interpreted using numerical models simulating the expected line emission from ablated material from the companion star. The spectral lines sought for are H alpha, [O I] lambda 6300, and [Ca II] lambda lambda 7291,7324, and the expected width of these lines is similar to 1000 km s(-1), which in the case of the [Ca II] lines blend to a broader feature. Results. No signs of H alpha, [O I] lambda 6300, or [Ca II] lambda lambda 7291, 7324 could be traced for in any of the two supernovae. When systematic uncertainties are included, the limits on hydrogen-rich ablated gas are 0 : 003 M-circle dot in SN 2011fe and 0 : 0085 M-circle dot in SN 2014J, where the limit for SN 2014J is the second lowest ever, and the limit for SN 2011fe is a revision of a previous limit. Limits are also put on helium-rich ablated gas, and here limits from [O I] lambda 6300 provide the upper mass limits 0 : 002 M-circle dot and 0 : 005 M-circle dot for SNe 2011fe and 2014J, respectively. These numbers are used in conjunction with other data to argue that these supernovae can stem from double-degenerate systems or from single-degenerate systems with a spun-up/spun-down super-Chandrasekhar white dwarf. For SN 2011fe, other types of hydrogen-rich donors can very likely be ruled out, whereas a main-sequence donor system with large intrinsic separation is still possible for SN 2014J. Helium-rich donor systems cannot be ruled out for any of the two supernovae, but the expected short delay time for such progenitors makes this possibility less likely, especially for SN 2011fe. Published data for SNe 1998bu, 2000cx, 2001el, 2005am, and 2005cf are used to constrain their origin. We emphasise that the results of this study depend on the sought-after lines emerging unattenuated from the central regions of the nebula. Detailed radiative transfer calculations with longer line lists than are presently used are needed to confirm that this is, in fact, true. Finally, the broad lines of SNe 2011fe and 2014J are discussed, and it is found that the [Ni II] lambda 7378 emission is redshifted by similar to+ 1300 km s(-1), as opposed to the known blueshift of similar to-1100 km s(-1) for SN 2011fe. [Fe II] lambda 7155 is also redshifted in SN 2014J. SN 2014J belongs to a minority of SNe Ia that both have a nebular redshift of [Fe II] lambda 7155 and [Ni II] lambda 7378, and a slow decline of the Si II lambda 6355 absorption trough just after B-band maximum.

  • 44.
    Lundqvist, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Tziamtzis, A.
    Stockholm University, Faculty of Science, Department of Astronomy. Korea Astronomy and Space Science Institute, Republic of Korea.
    Constraints on fast ejecta in the Crab supernova remnant from optical spectral lines2012In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 423, no 2, p. 1571-1582Article in journal (Refereed)
    Abstract [en]

    The low kinetic energy and mass of the Crab supernova remnant challenge our understanding of core-collapse supernova explosions. A possibility is that the Crab nebula is surrounded by a shell of fast ejecta containing the missing kinetic energy and mass. The only direct evidence for such a fast shell comes from an absorption feature in the Crab pulsar spectrum as a result of C iv?1550. The velocities inferred from the C iv line absorption extend to at least similar to 2500 km s-1, which is about twice as fast as the expansion of main shell of the remnant in our direction. We have searched for additional evidence of fast-moving ejecta in the optical spectra obtained with the FORS1 instrument at the European Southern Observatory (ESO) 8.2-m Very Large Telescope (VLT) and with the Andalucia Faint Object Spectrograph and Camera (ALFOSC) at the 2.56-m Nordic Optical Telescope (NOT), with the focus on absorption in Ca ii??3934,3968, and emission components in [O iii] ??4959,5007. The data are compared with the C iv?1550 absorption, and with theoretical expectations derived from shell models with ballistic gas motion, and a power-law density profile of the fast ejecta. Along the line of sight to the pulsar, we find that no gas in the nebula moves faster towards us than approximate to 1400 km s-1. We identify this gas as part of the known main shell of the remnant. This velocity agrees with previous results showing that the Crab nebula is moving slowly in this direction. It is slower than the velocity of 1680 km s-1 used in the models of Sollerman et al. as a minimum velocity of the presumed fast shell of supernova ejecta to account for the C iv line absorption. We find faster moving gas within 310 arcsec north and south of the pulsar, where the fastest gas moving towards us, as traced by [O iii], has a velocity of 16501700 km s-1. The fastest [O iii] emitting gas along the line of sight to the pulsar, on the rear side of the nebula, has a velocity of approximate to+1800 km s-1, which is higher than the velocity previously recorded for that direction. However, neither the [O iii] nor Ca ii lines display any signatures of fast shell ejecta at the velocities inferred from the C iv line absorption. To fully rule out the possibility that a chimney-like structure directed towards us could be responsible for the C iv line absorption, we need deep observations taken with 810-m class telescopes with good spectral resolution. We show that a spectral resolution better than similar to 200 km s-1 is needed to draw any conclusions on emission lines from gas moving towards us, along the line of sight of the pulsar, faster than similar to 1700 km s-1. To probe the fast shell ejecta, new observations from the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) should be substantially more powerful than the previous HST Space Telescope Imaging Spectrograph (STIS) data to fully explore the C iv?1550 absorption-line profile.

  • 45. Matsuura, M.
    et al.
    Dwek, E.
    Barlow, M. J.
    Babler, B.
    Baes, M.
    Meixner, M.
    Cernicharo, Jose
    Clayton, Geoff C.
    Dunne, L.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Fritz, Jacopo
    Gear, Walter
    Gomez, H. L.
    Groenewegen, M. A. T.
    Indebetouw, R.
    Ivison, R. J.
    Jerkstrand, A.
    Lebouteiller, V.
    Lim, T. L.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Pearson, C. P.
    Roman-Duval, J.
    Royer, P.
    Staveley-Smith, Lister
    Swinyard, B. M.
    van Hoof, P. A. M.
    van Loon, J. Th.
    Verstappen, Joris
    Wesson, Roger
    Zanardo, Giovanna
    Blommaert, Joris A. D. L.
    Decin, Leen
    Reach, W. T.
    Sonneborn, George
    Van de Steene, Griet C.
    Yates, Jeremy A.
    A STUBBORNLY LARGE MASS OF COLD DUST IN THE EJECTA OF SUPERNOVA 1987A2015In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 800, no 1, article id 50Article in journal (Refereed)
    Abstract [en]

    We present new Herschel photometric and spectroscopic observations of Supernova 1987A, carried out in 2012. Our dedicated photometric measurements provide new 70 mu m data and improved imaging quality at 100 and 160 mu m compared to previous observations in 2010. Our Herschel spectra show only weak CO line emission, and provide an upper limit for the 63 mu m [O-I] line flux, eliminating the possibility that line contaminations distort the previously estimated dustmass. The far-infrared spectral energy distribution (SED) is well fitted by thermal emission from cold dust. The newly measured 70 mu m flux constrains the dust temperature, limiting it to nearly a single temperature. The far-infrared emission can be fitted by 0.5 +/- 0.1M(circle dot) of amorphous carbon, about a factor of two larger than the current nucleosynthetic mass prediction for carbon. The observation of SiO molecules at early and late phases suggests that silicates may also have formed and we could fit the SED with a combination of 0.3M(circle dot) of amorphous carbon and 0.5M(circle dot) of silicates, totalling 0.8M(circle dot) of dust. Our analysis thus supports the presence of a large dust reservoir in the ejecta of SN 1987A. The inferred dust mass suggests that supernovae can be an important source of dust in the interstellar medium, from local to high-redshift galaxies.

  • 46. Matsuura, M.
    et al.
    Dwek, E.
    Meixner, M.
    Otsuka, M.
    Babler, B.
    Barlow, M. J.
    Roman-Duval, J.
    Engelbracht, C.
    Sandstrom, K.
    Lakicevic, M.
    van Loon, J. Th
    Sonneborn, G.
    Clayton, G. C.
    Long, K. S.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nozawa, T.
    Gordon, K. D.
    Hony, S.
    Panuzzo, P.
    Okumura, K.
    Misselt, K. A.
    Montiel, E.
    Sauvage, M.
    Herschel Detects a Massive Dust Reservoir in Supernova 1987A2011In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 333, no 6047, p. 1258-1261Article in journal (Refereed)
    Abstract [en]

    We report far-infrared and submillimeter observations of supernova 1987A, the star whose explosion was observed on 23 February 1987 in the Large Magellanic Cloud, a galaxy located 160,000 light years away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of about 17 to 23 kelvin at a rate of about 220 times the luminosity of the Sun. The intensity and spectral energy distribution of the emission suggest a dust mass of about 0.4 to 0.7 times the mass of the Sun. The radiation must originate from the supernova ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high redshifts.

  • 47. Matsuura, M.
    et al.
    Indebetouw, R.
    Woosley, S.
    Bujarrabal, V.
    Abellan, F. J.
    McCray, R.
    Kamenetzky, J.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Barlow, M. J.
    Gomez, H. L.
    Cigan, P.
    De Looze, I.
    Spyromilio, J.
    Staveley-Smith, L.
    Zanardo, G.
    Roche, P.
    Larsson, J.
    Viti, S.
    van Loon, J. Th.
    Wheeler, J. C.
    Baes, M.
    Chevalier, R.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Marcaide, J. M.
    Dwek, E.
    Meixner, M.
    Ng, C. -Y.
    Sonneborn, G.
    Yates, J.
    ALMA spectral survey of Supernova 1987A-molecular inventory, chemistry, dynamics and explosive nucleosynthesis2017In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 469, no 3, p. 3347-3362Article in journal (Refereed)
    Abstract [en]

    We report the first molecular line survey of Supernova 1987A in the millimetre wavelength range. In the Atacama Large Millimeter/submillimeter Array (ALMA) 210-300 and 340360 GHz spectra, we detected cold (20-170 K) CO, (SiO)-Si-28, HCO+ and SO, with weaker lines of 29SiO from ejecta. This is the first identification of HCO+ and SO in a young supernova remnant. We find a dip in the J = 6-5 and 5-4 SiO line profiles, suggesting that the ejecta morphology is likely elongated. The difference of theCOand SiO line profiles is consistent with hydrodynamic simulations, which showthat Rayleigh-Taylor instabilities causemixing of gas, with heavier elements much more disturbed, making more elongated structure. We obtained isotopologue ratios of (SiO)-Si-28/(SiO)-Si-29> 13, (SiO)-Si-28/(SiO)-Si-30> 14 and (CO)-C-12/(CO)-C-13 > 21, with the most likely limits of (SiO)-Si-28/(SiO)-Si-29 > 128, (SiO)-Si-28/(SiO)-Si-30 > 189. Low Si-29 and Si-30 abundances in SN 1987A are consistent with nucleosynthesis models that show inefficient formation of neutron-rich isotopes in a low-metallicity environment, such as the Large Magellanic Cloud. The deduced large mass of HCO+ (similar to 5 x 10(-6)M(circle dot)) and small SiS mass (< 6 x 10-5M(circle dot)) might be explained by some mixing of elements immediately after the explosion. The mixing might have caused some hydrogen from the envelope to sink into carbon- and oxygen-rich zones after the explosion, enabling the formation of a substantial mass of HCO+. Oxygen atoms may have penetrated into silicon and sulphur zones, suppressing formation of SiS. Our ALMA observations open up a new window to investigate chemistry, dynamics and explosive nucleosynthesis in supernovae.

  • 48.
    Mattila, S.
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, P.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Sollerman, J.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kozma, C.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Baron, E.
    Fransson, C.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Leibundgut, B.
    Nomoto, K.
    Early and late time VLT spectroscopy of SN 2001el - progenitor constraints for a type Ia supernova2005In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 443, p. 649-662Article in journal (Refereed)
    Abstract [en]

    We present early time high-resolution (VLT/UVES) and late time low-resolution (VLT/FORS) optical spectra of the normal type Ia supernova, SN 2001el. The high-resolution spectra were obtained 9 and 2 days before (B-band) maximum light. This was in order to allow the detection of narrow hydrogen and/or helium emission lines from the circumstellar medium of the supernova. No such lines were detected in our data. We therefore use these spectra together with photoionisation models to derive upper limits of 9×10-6 {M}_ȯ yr-1 and 5×10-5 {M}_ȯ yr-1 for the mass loss rate from the progenitor system of SN 2001el assuming velocities of 10 km s-1 and 50 km s-1, respectively, for a wind extending to outside at least a few × 1015 cm away from the supernova explosion site. So far, these are the best Hα based upper limits obtained for a type Ia supernova, and exclude a symbiotic star in the upper mass loss rate regime (so called Mira type stars) from being the progenitor of SN 2001el. The low-resolution spectrum was obtained in the nebular phase of the supernova, 400 days after the maximum light, to search for any hydrogen rich gas originating from the supernova progenitor system. However, we see no signs of Balmer lines in our spectrum. Therefore, we model the late time spectra to derive an upper limit of 0.03 Mȯ for solar abundance material present at velocities lower than 1000 km s-1 within the supernova explosion site. According to numerical simulations of Marietta et al. (2000) this is less than the expected mass lost by a subgiant, red giant or a main-sequence secondary star at a small binary separation as a result of the SN explosion. Our data therefore exclude these scenarios as the progenitor of SN 2001el. Finally, we discuss the origin of high velocity Ca II lines previously observed in a few type Ia supernovae before the maximum light. We see both the Ca II IR triplet and the H&K lines in our earliest (-9 days) spectrum at a very high velocity of up to 34 000 km s-1. The spectrum also shows a flat-bottomed Si II "6150 Å" feature similar to the one previously observed in SN 1990N (Leibundgut et al. 1991, ApJ, 371, L23) at 14 days before maximum light. We compare these spectral features in SN 2001el to those observed in SN 1984A and SN 1990N at even higher velocities.

  • 49. Mattila, S.
    et al.
    Perez-Torres, M.
    Efstathiou, A.
    Mimica, P.
    Fraser, M.
    Kankare, E.
    Alberdi, A.
    Aloy, M. A.
    Heikkila, T.
    Jonker, P. G.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Marti-Vidal, I.
    Meikle, W. P. S.
    Romero-Canizales, C.
    Smartt, S. J.
    Tsygankov, S.
    Varenius, E.
    Alonso-Herrero, A.
    Bondi, M.
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Herrero-Illana, R.
    Kangas, T.
    Kotak, R.
    Ramirez-Olivencia, N.
    Vaisanen, P.
    Beswick, R. J.
    Clements, D. L.
    Greimel, R.
    Harmanen, J.
    Kotilainen, J.
    Nandra, K.
    Reynolds, T.
    Ryder, S.
    Walton, N. A.
    Wiik, K.
    Östlin, Göran
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger2018In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 361, no 6401, p. 482-485Article in journal (Refereed)
    Abstract [en]

    Tidal disruption events (TDEs) are transient flares produced when a star is ripped apart by the gravitational field of a supermassive black hole (SMBH). We have observed a transient source in the western nucleus of the merging galaxy pair Arp 299 that radiated > 1.5 x 10(52) erg at infrared and radio wavelengths but was not luminous at optical or x-ray wavelengths. We interpret this as a TDE with much of its emission reradiated at infrared wavelengths by dust. Efficient reprocessing by dense gas and dust may explain the difference between theoretical predictions and observed luminosities of TDEs. The radio observations resolve an expanding and decelerating jet, probing the jet formation and evolution around a SMBH.

  • 50. Mattila, Seppo
    et al.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Gröningsson, Per
    Meikle, Peter
    Stathakis, Raylee
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cannon, Russell
    Abundances and Density Structure of the Inner Circumstellar Ring Around SN 1987A2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 717, no 2, p. 1140-1156Article in journal (Refereed)
    Abstract [en]

    We present optical spectroscopic data of the inner circumstellar ring around supernova (SN) 1987A from the Anglo-Australian Telescope and the Very Large Telescope (VLT) between ~1400 and ~5000 days post-explosion. We also assembled the available optical and near-infrared line fluxes from the literature between ~300 and ~2000 days. These line light curves were fitted with a photoionization model to determine the density structure and the elemental abundances for the inner ring. We found densities ranging from 1 × 103 to 3 × 104 atoms cm-3 and a total mass of the ionized gas of ~5.8 × 10-2 M sun within the inner ring. Abundances inferred from the optical and near-infrared data were also complemented with estimates of Lundqvist & Fransson based on ultraviolet lines. This way we found an He/H ratio (by number of atoms) of 0.17 ± 0.06 which is roughly 30% lower than previously estimated and twice the solar and the Large Magellanic Cloud (LMC) value. We found an N/O ratio of 1.5 ± 0.7, and the total (C+N+O)/(H+He) abundance about 1.6 times its LMC value or roughly 0.6 times the most recent solar value. An iron abundance of 0.20 ± 0.11 times solar was found which is within the range of the estimates for the LMC. We also present late time (~5000-7500 days) line light curves of [O III], [Ne III], [Ne IV], [Ar III], [Ar IV], and [Fe VII] from observations with the VLT. We compared these with model fluxes and found that an additional 102 atoms cm-3 component was required to explain the data of the highest ionization lines. Such low-density gas is expected in the H II-region interior to the inner ring which likely extends also to larger radii at higher latitudes (out of the ring plane). At epochs later than ~5000 days, our models underproduce the emission of most of these lines as expected due to the contribution from the interaction of the SN ejecta with the ring.

12 1 - 50 of 86
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf