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  • 1. Beswick, R. J.
    et al.
    Perez-Torres, M. A.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Garrington, S. T.
    Kankare, E.
    Ryder, S.
    Alberdi, A.
    Romero-Canizales, C.
    MERLIN radio observations of two recent supernovae in Arp299: SN2010O & SN2010P2010Report (Other academic)
    Abstract [en]

    We report MERLIN radio observations of the two recent supernovae in Arp299; SN2010P and SN2010O (CBET #2145 and CBET #2144, respectively). Observations of Arp299 were made between 1900UT 29th Jan 2010 and 0150UT 1st Feb 2010 at 4994MHz. The previously known compact radio structure of Arp299, including the nuclear starburst components associated with A=IC694 and B1=the southernmost nucleus of NGC3690 are detected (Neff, Ulvestad & Teng 2004, ApJ, 611, 186; Ulvestad 2009 AJ, 138, 152; Perez-Torres et al 2009, A&A 507, 17).

  • 2. Boles, T.
    et al.
    Smartt, S. J.
    Valenti, S.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kankare, E.
    Katajainen, S.
    Bird, S. A.
    Pursimo, T.
    Supernova 2010ik in UGC 1122010Report (Other academic)
  • 3. Botticella, M. T.
    et al.
    Trundle, C.
    Pastorello, A.
    Rodney, S.
    Rest, A.
    Gezari, S.
    Smartt, S. J.
    Narayan, G.
    Huber, M. E.
    Tonry, J. L.
    Young, D.
    Smith, K.
    Bresolin, F.
    Valenti, S.
    Kotak, R.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kankare, E.
    Wood-Vasey, W. M.
    Riess, A.
    Neill, J. D.
    Forster, K.
    Martin, D. C.
    Stubbs, C. W.
    Burgett, W. S.
    Chambers, K. C.
    Dombeck, T.
    Flewelling, H.
    Grav, T.
    Heasley, J. N.
    Hodapp, K. W.
    Kaiser, N.
    Kudritzki, R.
    Luppino, G.
    Lupton, R. H.
    Magnier, E. A.
    Monet, D. G.
    Morgan, J. S.
    Onaka, P. M.
    Price, P. A.
    Rhoads, P. H.
    Siegmund, W. A.
    Sweeney, W. E.
    Wainscoat, R. J.
    Waters, C.
    Waterson, M. F.
    Wynn-Williams, C. G.
    Supernova 2009kf: An Ultraviolet Bright Type IIP Supernova Discovered with Pan-STARRS 1 and GALEX2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 717, p. L52-L56Article in journal (Refereed)
    Abstract [en]

    We present photometric and spectroscopic observations of a luminous Type IIP Supernova (SN) 2009kf discovered by the Pan-STARRS 1 (PS1) survey and also detected by the Galaxy Evolution Explorer. The SN shows a plateau in its optical and bolometric light curves, lasting approximately 70 days in the rest frame, with an absolute magnitude of M V = -18.4 mag. The P-Cygni profiles of hydrogen indicate expansion velocities of 9000 km s-1 at 61 days after discovery which is extremely high for a Type IIP SN. SN 2009kf is also remarkably bright in the near-ultraviolet (NUV) and shows a slow evolution 10-20 days after optical discovery. The NUV and optical luminosity at these epochs can be modeled with a blackbody with a hot effective temperature (T ~ 16,000 K) and a large radius (R ~ 1 × 1015 cm). The bright bolometric and NUV luminosity, the light curve peak and plateau duration, the high velocities, and temperatures suggest that 2009kf is a Type IIP SN powered by a larger than normal explosion energy. Recently discovered high-z SNe (0.7 < z < 2.3) have been assumed to be IIn SNe, with the bright UV luminosities due to the interaction of SN ejecta with a dense circumstellar medium. UV-bright SNe similar to SN 2009kf could also account for these high-z events, and its absolute magnitude M NUV = -21.5 ± 0.5 mag suggests such SNe could be discovered out to z ~ 2.5 in the PS1 survey.

  • 4. Gezari, S.
    et al.
    Rest, A.
    Huber, M. E.
    Narayan, G.
    Forster, K.
    Neill, J. D.
    Martin, D. C.
    Valenti, S.
    Smartt, S. J.
    Chornock, R.
    Berger, E.
    Soderberg, A. M.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kankare, E.
    Burgett, W. S.
    Chambers, K. C.
    Dombeck, T.
    Grav, T.
    Heasley, J. N.
    Hodapp, K. W.
    Jedicke, R.
    Kaiser, N.
    Kudritzki, R.
    Luppino, G.
    Lupton, R. H.
    Magnier, E. A.
    Monet, D. G.
    Morgan, J. S.
    Onaka, P. M.
    Price, P. A.
    Rhoads, P. H.
    Siegmund, W. A.
    Stubbs, C. W.
    Tonry, J. L.
    Wainscoat, R. J.
    Waterson, M. F.
    Wynn-Williams, C. G.
    GALEX and Pan-STARRS1 Discovery of SN IIP 2010aq: The First Few Days After Shock Breakout in a Red Supergiant Star2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 720, p. L77-L81Article in journal (Refereed)
    Abstract [en]

    We present the early UV and optical light curve of Type IIP supernova (SN) 2010aq at z = 0.0862, and compare it to analytical models for thermal emission following SN shock breakout in a red supergiant star. SN 2010aq was discovered in joint monitoring between the Galaxy Evolution Explorer (GALEX) Time Domain Survey (TDS) in the NUV and the Pan-STARRS1 Medium Deep Survey (PS1 MDS) in the g, r, i, and z bands. The GALEX and Pan-STARRS1 observations detect the SN less than 1 day after the shock breakout, measure a diluted blackbody temperature of 31, 000 ± 6000 K 1 day later, and follow the rise in the UV/optical light curve over the next 2 days caused by the expansion and cooling of the SN ejecta. The high signal-to-noise ratio of the simultaneous UV and optical photometry allows us to fit for a progenitor star radius of 700 ± 200R sun, the size of a red supergiant star. An excess in UV emission two weeks after shock breakout compared with SNe well fitted by model atmosphere-code synthetic spectra with solar metallicity is best explained by suppressed line blanketing due to a lower metallicity progenitor star in SN 2010aq. Continued monitoring of PS1 MDS fields by the GALEX TDS will increase the sample of early UV detections of Type II SNe by an order of magnitude and probe the diversity of SN progenitor star properties.

  • 5. Kankare, E.
    et al.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Valenti, S.
    Smartt, S.
    Young, D.
    Smith, K.
    Chornock, R.
    Edge, A.
    Bresolin, F.
    Kudritzki, R.
    Tonry, J.
    Price, P. A.
    Magnier, E.
    Chambers, K.
    Kaiser, N.
    Morgan, J.
    Burgett, W.
    Heasley, J.
    Sweeney, W.
    Waters, C.
    Flewelling, H.
    Discovery of two new supernovae and an AGN outburst by PS12010Report (Other academic)
    Abstract [en]

    We report the discovery of two spectroscopically-confirmed Supernovae PS1-1000302 and PS1-1000303, and an AGN outburst PS1-1000305 in the Pan-STARRS1 "3Pi Faint galaxy supernova survey". PS1-1000302 was detected on June 12.4 UT (g=18.5) at 16:33:43.094 +54:42:04.18 (J2000) located 1.1" from the center of the host galaxy SDSS J163343.08+544205.4. PS1-1000303 was detected on June 14.3 UT (g=19.2) at 17:11:52.827 +43:36:57.06 (J2000) located 0.4" from the center of the host galaxy SDSS J171152.82+433656.7.

  • 6. Kankare, E.
    et al.
    Mattila, Seppo
    Stockholm University, Faculty of Science, Department of Astronomy.
    Ryder, S.
    Perez-Torres, M. A.
    Romero-Canizales, C.
    Alberdi, A.
    Alonso-Herrero, A.
    Colina, L.
    Efstathiou, A.
    Kotilainen, J.
    Vaisanen, P.
    Possible Supernova in IC 883: Psn K1002-12010Report (Other academic)
  • 7. Kankare, E.
    et al.
    Pastorello, A.
    Valenti, S.
    Mattila, Seppo
    Stockholm University, Faculty of Science, Department of Astronomy.
    Chornock, R.
    Foley, R.
    Rest, A.
    Narayan, G.
    Huber, M.
    Young, D.
    Smith, K.
    Smartt, S.
    Tonry, J.
    Price, P. A.
    Stubbs, C.
    Riess, A.
    Wood-Vasey, W. M.
    Berger, E.
    Supernovae 2010aq, 2010ar, and 2010bb-2010bg2010Report (Other academic)
  • 8.
    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.

  • 9.
    Mattila, Seppo
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kankare, E.
    Supernova 2010P in Arp 2992010Report (Other academic)
  • 10.
    Mattila, Seppo
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kankare, E.
    Datson, J.
    Pastorello, A.
    Supernovae 2010O and 2010P2010Report (Other academic)
  • 11. Mazzali, P. A.
    et al.
    Benetti, S.
    Altavilla, G.
    Blanc, G.
    Cappellaro, E.
    Elias-Rosa, N.
    Garavini, G.
    Stockholm University, Faculty of Science, Department of Physics.
    Goobar, A.
    Stockholm University, Faculty of Science, Department of Physics.
    Harutyunyan, A.
    Kotak, R.
    Leibundgut, B.
    Lundqvist, P.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mendez, J.
    Nobili, S.
    Stockholm University, Faculty of Science, Department of Physics.
    Pain, R.
    Pastorello, A.
    Patat, F.
    Pignata, G.
    Podsiadlowski, Ph.
    Ruiz-Lapuente, P.
    Salvo, M.
    Schmidt, B. P.
    Sollerman, J.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Stanishev, V.
    Stockholm University, Faculty of Science, Department of Physics.
    Stehle, M.
    Tout, C.
    Turatto, M.
    Hillebrandt, W.
    High-Velocity Features: A Ubiquitous Property of Type Ia Supernovae2005In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 623, p. L37-L40Article in journal (Refereed)
    Abstract [en]

    Evidence of high-velocity features (HVFs) such as those seen in the near-maximum spectra of some Type Ia supernovae (SNe Ia; e.g., SN 2000cx) has been searched for in the available SN Ia spectra observed earlier than 1 week before B maximum. Recent observational efforts have doubled the number of SNe Ia with very early spectra. Remarkably, all SNe Ia with early data (seven in our Research Training Network sample and 10 from other programs) show signs of such features, to a greater or lesser degree, in Ca II IR and some also in the Si II λ6355 line. HVFs may be interpreted as abundance or density enhancements. Abundance enhancements would imply an outer region dominated by Si and Ca. Density enhancements may result from the sweeping up of circumstellar material (CSM) by the highest velocity SN ejecta. In this scenario, the high incidence of HVFs suggests that a thick disk and/or a high-density companion wind surrounds the exploding white dwarf, as may be the case in single degenerate systems. Large-scale angular fluctuations in the radial density and abundance distribution may also be responsible: this could originate in the explosion and would suggest a deflagration as the more likely explosion mechanism. CSM interaction and surface fluctuations may coexist, possibly leaving different signatures on the spectrum. In some SNe, the HVFs are narrowly confined in velocity, suggesting the ejection of blobs of burned material.

  • 12. Meikle, W. P. S.
    et al.
    Mattila, S.
    Gerardy, C. L.
    Kotak, R.
    Pozzo, M.
    van Dyk, S. D.
    Farrah, D.
    Fesen, R. A.
    Filippenko, A. V.
    Fransson, C.
    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.
    Wheeler, J. C.
    A Spitzer Space Telescope Study of SN 2002hh: An Infrared Echo from a Type IIP Supernova2006In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 649, p. 332-344Article in journal (Refereed)
    Abstract [en]

    We present late-time (590-994 days) mid-IR photometry of the normal but highly reddened Type IIP supernova SN 2002hh. Bright, cool, slowly fading emission is detected from the direction of the supernova. Most of this flux appears not to be driven by the supernova event but instead probably originates in a cool, obscured star formation region or molecular cloud along the line of sight. We also show, however, that the declining component of the flux is consistent with an SN-powered IR echo from a dusty progenitor CSM. Mid-IR emission could also be coming from newly condensed dust and/or an ejecta/CSM impact, but their contributions are likely to be small. For the case of a CSM-IR echo, we infer a dust mass of as little as 0.036 Msolar with a corresponding CSM mass of 3.6(0.01/rdg) Msolar, where rdg is the dust-to-gas mass ratio. Such a CSM would have resulted from episodic mass loss whose rate declined significantly about 28,000 years ago. Alternatively, an IR echo from a surrounding, dense, dusty molecular cloud might also have been responsible for the fading component. Either way, this is the first time that an IR echo has been clearly identified in a Type IIP supernova. We find no evidence for or against the proposal that Type IIP supernovae produce large amounts of dust via grain condensation in the ejecta. However, within the CSM-IR echo scenario, the mass of dust derived implies that the progenitors of the most common of core-collapse supernovae may make an important contribution to the universal dust content.

  • 13. Pastorello, A.
    et al.
    Smartt, S. J.
    Botticella, M. T.
    Maguire, K.
    Fraser, M.
    Smith, K.
    Kotak, R.
    Magill, L.
    Valenti, S.
    Young, D. R.
    Gezari, S.
    Bresolin, F.
    Kudritzki, R.
    Howell, D. A.
    Rest, A.
    Metcalfe, N.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kankare, E.
    Huang, K. Y.
    Urata, Y.
    Burgett, W. S.
    Chambers, K. C.
    Dombeck, T.
    Flewelling, H.
    Grav, T.
    Heasley, J. N.
    Hodapp, K. W.
    Kaiser, N.
    Luppino, G. A.
    Lupton, R. H.
    Magnier, E. A.
    Monet, D. G.
    Morgan, J. S.
    Onaka, P. M.
    Price, P. A.
    Rhoads, P. H.
    Siegmund, W. A.
    Stubbs, C. W.
    Sweeney, W. E.
    Tonry, J. L.
    Wainscoat, R. J.
    Waterson, M. F.
    Waters, C.
    Wynn-Williams, C. G.
    Ultra-bright Optical Transients are Linked with Type Ic Supernovae2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 724, p. L16-L21Article in journal (Refereed)
    Abstract [en]

    Recent searches by unbiased, wide-field surveys have uncovered a group of extremely luminous optical transients. The initial discoveries of SN 2005ap by the Texas Supernova Search and SCP-06F6 in a deep Hubble pencil beam survey were followed by the Palomar Transient Factory confirmation of host redshifts for other similar transients. The transients share the common properties of high optical luminosities (peak magnitudes ~-21 to -23), blue colors, and a lack of H or He spectral features. The physical mechanism that produces the luminosity is uncertain, with suggestions ranging from jet-driven explosion to pulsational pair instability. Here, we report the most detailed photometric and spectral coverage of an ultra-bright transient (SN 2010gx) detected in the Pan-STARRS 1 sky survey. In common with other transients in this family, early-time spectra show a blue continuum and prominent broad absorption lines of O II. However, about 25 days after discovery, the spectra developed type Ic supernova features, showing the characteristic broad Fe II and Si II absorption lines. Detailed, post-maximum follow-up may show that all SN 2005ap and SCP-06F6 type transients are linked to supernovae Ic. This poses problems in understanding the physics of the explosions: there is no indication from late-time photometry that the luminosity is powered by 56Ni, the broad light curves suggest very large ejected masses, and the slow spectral evolution is quite different from typical Ic timescales. The nature of the progenitor stars and the origin of the luminosity are intriguing and open questions.

  • 14. Pastorello, A.
    et al.
    Smartt, S. J.
    Kankare, D.
    Young, E.
    Smith, K.
    Botticella, M. T.
    Mattila, Seppo
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kotak, R.
    Valenti, S.
    Metcalfe, N.
    Sweeney, W. E.
    Price, P. A.
    Magnier, E.
    Tonry, J.
    Bresolin, F.
    Kudritzki, R. P.
    Chambers, K.
    Stubbs, C.
    Rest, A.
    Narayan, G.
    Riess, A.
    Huber, M.
    Wood-Vasey, W. M.
    Detection of PTF10cwr/CSS100313 on PS1 sky survey images and host galaxy identification2010Report (Other academic)
    Abstract [en]

    We report that the transient PTF10cwr (Quimby et al. ATEL #2492), a.k.a. CSS100313:112547-084941 (Mahabal et al. ATel #2490), was also recovered on images from the Pan-STARRS Telescope #1 (PS1) as part of the PS1 3Pi survey (PS1-1000037). Magnitudes of i=18.96 and r=18.65 where measured with respect to SDSS sequence stars on March 12.45 and 13.49 UT respectively. Further photometry was gathered at the Liverpool Telescope on March 20.92 and March 23.00 UT.

  • 15. Ryder, S.
    et al.
    Kankare, E.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Supernova 2010cu in IC 883 = Psn K1002-12010Report (Other academic)
  • 16. Ryder, S.
    et al.
    Mattila, Seppo
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kankare, E.
    Perez-Torres, M.
    Supernova 2010P2010Report (Other academic)
  • 17.
    Sollerman, J.
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Cox, N.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Ehrenfreund, P.
    Kaper, L.
    Leibundgut, B.
    Lundqvist, P.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Diffuse Interstellar Bands in NGC 14482005In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 429, p. 559-567Article in journal (Refereed)
    Abstract [en]

    We present spectroscopic VLT/UVES observations of two emerging supernovae, the Type Ia SN 2001el and the Type II SN 2003hn, in the spiral galaxy NGC 1448. Our high resolution and high signal-to-noise spectra display atomic lines of Ca II, Na I, Ti II and K I in the host galaxy. In the line of sight towards SN 2001el, we also detect over a dozen diffuse interstellar bands (DIBs) within NGC 1448. These DIBs have strengths comparable to low reddening galactic lines of sight, albeit with some variations. In particular, a good match is found with the line of sight towards the σ type diffuse cloud (HD 144217). The DIBs towards SN 2003hn are significantly weaker, and this line of sight has also lower sodium column density. The DIB central velocities show that the DIBs towards SN 2001el are closely related to the strongest interstellar Ca II and Na I components, indicating that the DIBs are preferentially produced in the same cloud. The ratio of the λ 5797 and λ 5780 DIB strengths (r ˜ 0.14) suggests a rather strong UV field in the DIB environment towards SN 2001el. We also note that the extinction estimates obtained from the sodium lines using multiple line fitting agree with reddening estimates based on the colors of the Type Ia SN 2001el. Based on observations collected at the European Southern Observatory, Paranal, Chile (ESO Programmes 67.D-0227 and 71.D-0033). Table \ref{tb:ISfit} and Figs. \ref{fig:IS_MW} and \ref{fig:6284} are only available in electronic form at http://www.edpsciences.org

  • 18. Stathakis, R.
    et al.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Cannon, R.
    Lundqvist, P.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Meikle, P.
    Corbett, E.
    Optical studies of the ring around SN 1987A2004In: Anglo-Australian Observatory Newsletter, Vol. 104, p. 6-Article in journal (Other academic)
  • 19. Vaisanen, Petri
    et al.
    Randriamanakoto, Zara
    Kankare, Erkki
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Ryder, Stuart
    Super star clusters and Supernovae in interacting LIRGs unmasked by NIR adaptive optics2010In: proceedings of 'Galaxies and their Masks' (Namibia, April 2010), published by Springer / [ed] D.L. Block, K.C. Freeman, I. Puerari, 2010Conference paper (Other academic)
    Abstract [en]

    We report on an on-going near-IR adaptive optics survey targeting interacting luminous IR galaxies. High-spatial resolution NIR data are crucial to enable interpretation of kinematic, dynamical and star formation (SF) properties of these very dusty objects. Whole progenitor nuclei in the interactions can be missed if only optical HST imaging is used. Here we specifically present the latest results regarding core-collapse supernovae found within the highly extincted nuclear regions of these galaxies. Direct detection and study of such highly obscured CCSNe is crucial for revising the optically-derived SN rates used for providing an independent measurement of the SF history of the Universe. We also present thus-far the first NIR luminosity functions of super star cluster (SSC) candidates. The LFs can then be used to constrain the formation and evolution of SSCs via constraints based on initial mass functions and cluster disruption models.

  • 20. Valenti, S.
    et al.
    Kankare, E.
    Mattila, S.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pastorello, A.
    Smartt, S.
    Smith, K.
    Kotak, R.
    Ward, M.
    Gezari, S.
    Chornock, R.
    Bresolin, F.
    Kudritzki, R.
    Tonry, J.
    Magnier, E.
    Chambers, K.
    Kaiser, N.
    Morgan, J.
    Burgett, W.
    Heasley, J.
    Sweeney, W.
    Waters, C.
    Flewelling, H.
    Price, P. A.
    Discovery of two new supernovae and a possible AGN/luminous SN IIn in the Pan-STARRS1 3Pi faint galaxy supernova survey2010Report (Other academic)
    Abstract [en]

    report the discovery of two new supernovae and a possible AGN/luminous SN IIn in the Pan-STARRS 1 "3Pi Faint galaxy supernova survey". During the course of the PS1 3Pi sky survey, PS1-1000791 was detected on Aug 14.40 (UT) (Coord: 20:45:13.089 -06:56:11.090, J2000) at g=19.4 and detected again on Aug 19.33 at r=18.64 within 0.9 arcsec of the faint SDSS galaxy (J204513.14-065611.2). A spectrum of PS1-1000791 was obtained at the Nordic Optical Telescope (+ALFOSC+Gr4; range 350-950nm) on Aug 30.0 (UT).

  • 21. Väisänen, Petri
    et al.
    Mattila, Seppo
    Stockholm University, Faculty of Science, Department of Astronomy.
    Ryder, Stuart
    Star Formation Properties and Dynamics of Luminous Infrared Galaxies with Adaptive Optics2010In: Galaxy Wars: Stellar Populations and Star Formation in Interacting Galaxies : proceedings of a conference held 19-22 July 2009 at East Tennessee State University, Johnson City, Tennessee, USA. / [ed] Beverly Smith, Nate Bastian, Sarah J. U. Higdon, and James L. Higdon, San Francisco: Astronomical Society of the Pacific , 2010, Vol. 423, p. 323-Conference paper (Other academic)
    Abstract [en]

    Near infrared adaptive optics observations are crucial to be able to interpret kinematic and dynamical data and study star formation properties within the often extremely dusty interacting luminous IR galaxies (LIRGs). NIR AO data are also needed to find supernovae in their bright and dusty central regions and to fully characterize the young stellar clusters found in these kinds of systems. We have used AO in the K-band to survey a sample of LIRGs at 0.1 arcsec (30 to 100 pc) resolution. The data are merged with SALT and AAT spectroscopic follow-up and HST and Spitzer archival imaging. The first AO detected SNe are reported as well as details of the first studied LIRGs. One LIRG showed an unexpected third component in the interaction, which moreover turned out to host the most active star formation. Another target showed evidence in the NIR of a very rare case of leading spiral arms, rotating in the same direction as the arms open.

  • 22. Young, D. R.
    et al.
    Smartt, S. J.
    Valenti, S.
    Pastorello, A.
    Benetti, S.
    Benn, C. R.
    Bersier, D.
    Botticella, M. T.
    Corradi, R. L. M.
    Harutyunyan, A. H.
    Hrudkova, M.
    Hunter, I.
    Mattila, Seppo
    Stockholm University, Faculty of Science, Department of Astronomy.
    de Mooij, E. J. W.
    Navasardyan, H.
    Snellen, I. A. G.
    Tanvir, N. R.
    Zampieri, L.
    Two type Ic supernovae in low-metallicity, dwarf galaxies: diversity of explosions2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 512, p. 70-Article in journal (Refereed)
    Abstract [en]

    Aims: The aim of this paper is to discuss the nature of two type Ic supernovae SN 2007bg and SN 2007bi and their host galaxies. Both supernovae were discovered in wide-field, non-targeted surveys and are found to be associated with sub-luminous blue dwarf galaxies identified in SDSS images. Methods: We present BVRI photometry and optical spectroscopy of SN 2007bg and SN 2007bi and their host galaxies. Their lightcurves and spectra are compared to those of other type Ic SNe and analysis of these data provides estimates of the energetics, total ejected masses and synthesised mass of 56Ni. Detection of the host galaxy emission lines allows for metallicity measurements. Results: Neither SNe 2007bg nor 2007bi were found in association with an observed GRB, but from estimates of the metallicities of their host-galaxies they are found to inhabit similar low-metallicity environments as GRB associated supernovae. The radio-bright SN 2007bg is hosted by an extremely sub-luminous galaxy of magnitude MB = -12.4 ± 0.6 mag and an estimated oxygen abundance of 12+log(O/H) = 8.18 ± 0.17 (on the Pettini & Pagel 2004 scale). The early lightcurve evolution of SN 2007bg matches the fast-pace decline of SN 1994I giving it one of the fastest post-maximum decline rates of all broad-lined type Ic supernovae known to date and, when combined with its high expansion velocities, a high kinetic energy to ejected mass ratio (EK/Mej~2.7). We also show that SN 2007bi is possibly the most luminous type Ic known, reaching a peak magnitude of MR ~ -21.3 mag and displays a remarkably slow decline, following the radioactive decay rate of 56Co to 56Fe throughout the course of its observed lifetime. SN 2007bi also displays an extreme longevity in its spectral evolution and is still not fully nebular at approximately one year post-maximum brightness. From a simple model of the bolometric light curve of SN 2007bi we estimate a total ejected 56Ni mass of MNi = 3.5-4.5 M_ȯ, the largest 56Ni mass measured in the ejecta of a supernova to date. There are two models that could explain the high luminosity and large ejected 56Ni mass. One is a pair-instability supernova (PISN) which has been predicted to occur for massive stars at low metallicities. We measure the host galaxy metallicity of SN 2007bi to be 12+log(O/H) = 8.15 ± 0.15 (on the McGaugh 1991 scale) which is somewhat high to be consistent with the PISN model. An alternative is the core-collapse of a C+O star of 20-40 Mȯ which is the core of a star of originally 50-100 Mȯ.

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