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  • 51. Marshall, J. P.
    et al.
    Moro-Martin, A.
    Eiroa, C.
    Kennedy, G.
    Mora, A.
    Sibthorpe, B.
    Lestrade, J-E
    Maldonado, J.
    Sanz-Forcada, J.
    Wyatt, M. C.
    Matthews, B.
    Horner, J.
    Montesinos, B.
    Bryden, G.
    del Burgo, C.
    Greaves, J. S.
    Ivison, R. J.
    Meeus, G.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pilbratt, G. L.
    White, G. J.
    Correlations between the stellar, planetary, and debris components of exoplanet systems observed by Herschel2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 565, p. A15-Article in journal (Refereed)
    Abstract [en]

    Context. Stars form surrounded by gas- and dust-rich protoplanetary discs. Generally, these discs dissipate over a few (3-10) Myr, leaving a faint tenuous debris disc composed of second-generation dust produced by the attrition of larger bodies formed in the protoplanetary disc. Giant planets detected in radial velocity and transit surveys of main-sequence stars also form within the protoplanetary disc, whilst super-Earths now detectable may form once the gas has dissipated. Our own solar system, with its eight planets and two debris belts, is a prime example of an end state of this process. Aims. The Herschel DEBRIS, DUNES, and GI' programmes observed 37 exoplanet host stars within 25 pc at 70, 100, and 160 mu m with the sensitivity to detect far-infrared excess emission at flux density levels only an order of magnitude greater than that of the solar system's Edgeworth-Kuiper belt. Here we present an analysis of that sample, using it to more accurately determine the (possible) level of dust emission from these exoplanet host stars and thereafter determine the links between the various components of these exoplanetary systems through statistical analysis. Methods. We have fitted the flux densities measured from recent Herschel observations with a simple two parameter (T-d, L-IR/L-*) black-body model (or to the 3 sigma upper limits at 100 mu m). From this uniform approach we calculated the fractional luminosity, radial extent and dust temperature. We then plotted the calculated dust luminosity or upper limits against the stellar properties, e.g. effective temperature, metallicity, and age, and identified correlations between these parameters. Results. A total of eleven debris discs are identified around the 37 stars in the sample. An incidence of ten cool debris discs around the Sun-like exoplanet host stars (29 +/- 9%) is consistent with the detection rate found by DUNES (20.2 +/- 2.0%). For the debris disc systems, the dust temperatures range from 20 to 80 K, and fractional luminosities (L-IR/L-*) between 2.4 x10(-6) and 4.1 x10(-4). In the case of non-detections, we calculated typical 3 sigma upper limits to the dust fractional luminosities of a few x10(-6). Conclusions. We recover the previously identified correlation between stellar metallicity and hot-Jupiter planets in our data set. We find a correlation between the increased presence of dust, lower planet masses, and lower stellar metallicities. This confirms the recently identified correlation between cold debris discs and low-mass planets in the context of planet formation by core accretion.

  • 52. Matthews, Brenda C.
    et al.
    Kennedy, Grant
    Sibthorpe, Bruce
    Holland, Wayne
    Booth, Mark
    Kalas, Paul
    MacGregor, Meredith
    Wilner, David
    Vandenbussche, Bart
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Blommaert, Joris
    Brandeker, Alexis
    Stockholm University, Faculty of Science, Department of Astronomy.
    Dent, W. R. F.
    de Vries, Bernard L.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Di Francesco, James
    Fridlund, Malcolm
    Graham, James R.
    Greaves, Jane
    Heras, Ana M.
    Hogerheijde, Michiel
    Ivison, R. J.
    Pantin, Eric
    Pilbratt, Goran L.
    THE AU MIC DEBRIS DISK: FAR-INFRARED AND SUBMILLIMETER RESOLVED IMAGING2015In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 811, no 2, article id 100Article in journal (Refereed)
    Abstract [en]

    We present far-infrared and submillimeter maps from the Herschel Space Observatory and the James Clerk Maxwell Telescope of the debris disk host star AU Microscopii. Disk emission is detected at 70, 160, 250, 350, 450, 500, and 850 mu m. The disk is resolved at 70, 160, and 450 mu m. In addition to the planetesimal belt, we detect thermal emission from AU Mic's halo for the first time. In contrast to the scattered light images, no asymmetries are evident in the disk. The fractional luminosity of the disk is 3.9 x 10(-4) and its milimeter-grain dust mass is 0.01 M-circle dot (+/- 20%). We create a simple spatial model that reconciles the disk spectral energy distribution as a blackbody of 53 +/- 2K (a composite of 39 and 50 K components) and the presence of small (non-blackbody) grains which populate the extended halo. The best-fit model is consistent with the birth ring model explored in earlier works, i.e., an edge-on dust belt extending from 8.8 to 40 AU, but with an additional halo component with an r(-1.5) surface density profile extending to the limits of sensitivity (140 AU). We confirm that AU Mic does not exert enough radiation force to blow out grains. For stellar mass-loss rates of 10-100 times solar, compact (zero porosity) grains can only be removed if they are very small; consistently with previous work, if the porosity is 0.9, then grains approaching 0.1 mu m can be removed via corpuscular forces (i.e., the stellar wind).

  • 53. Men'shchikov, A.
    et al.
    Andre, Ph.
    Didelon, P.
    Koenyves, V.
    Schneider, N.
    Motte, F.
    Bontemps, S.
    Arzoumanian, D.
    Attard, M.
    Abergel, A.
    Baluteau, J. -P
    Bernard, J. -Ph.
    Cambresy, L.
    Cox, P.
    Di Francesco, J.
    Di Giorgio, A. M.
    Griffin, M.
    Hargrave, P.
    Huang, M.
    Kirk, J.
    Li, J. Z.
    Martin, P.
    Minier, V.
    Miville-Deschenes, M. -A
    Molinari, S.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pezzuto, S.
    Roussel, H.
    Russeil, D.
    Saraceno, P.
    Sauvage, M.
    Sibthorpe, B.
    Spinoglio, L.
    Testi, L.
    Ward-Thompson, D.
    White, G.
    Wilson, C. D.
    Woodcraft, A.
    Zavagno, A.
    Filamentary structures and compact objects in the Aquila and Polaris clouds observed by Herschel2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 518, p. L103-Article in journal (Refereed)
    Abstract [en]

    Our PACS and SPIRE images of the Aquila Rift and part of the Polaris Flare regions, taken during the science demonstration phase of Herschel discovered fascinating, omnipresent filamentary structures that appear to be physically related to compact cores. We briefly describe a new multi-scale, multi-wavelength source extraction method used to detect objects and measure their parameters in our Herschel images. All of the extracted starless cores (541 in Aquila and 302 in Polaris) appear to form in the long and very narrow filaments. With its combination of the far-IR resolution and sensitivity, Herschel directly reveals the filaments in which the dense cores are embedded; the filaments are resolved and have deconvolved widths of similar to 35 '' in Aquila and similar to 59 '' in Polaris (similar to 9000 AU in both regions). Our first results of observations with Herschel enable us to suggest that in general dense cores may originate in a process of fragmentation of complex networks of long, thin filaments, likely formed as a result of an interplay between gravity, interstellar turbulence, and magnetic fields. To unravel the roles of the processes, one has to obtain additional kinematic and polarization information; these follow-up observations are planned.

  • 54. Motte, F.
    et al.
    Zavagno, A.
    Bontemps, S.
    Schneider, N.
    Hennemann, M.
    Di Francesco, J.
    Andre, Ph.
    Saraceno, P.
    Griffin, M.
    Marston, A.
    Ward-Thompson, D.
    White, G.
    Minier, V.
    Men'shchikov, A.
    Hill, T.
    Abergel, A.
    Anderson, L. D.
    Aussel, H.
    Balog, Z.
    Baluteau, J. -P
    Bernard, J. -Ph.
    Cox, P.
    Csengeri, T.
    Deharveng, L.
    Didelon, P.
    di Giorgio, A. -M
    Hargrave, P.
    Huang, M.
    Kirk, J.
    Leeks, S.
    Li, J. Z.
    Martin, P.
    Molinari, S.
    Nguyen-Luong, Q.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Persi, P.
    Peretto, N.
    Pezzuto, S.
    Roussel, H.
    Russeil, D.
    Sadavoy, S.
    Sauvage, M.
    Sibthorpe, B.
    Spinoglio, L.
    Testi, L.
    Teyssier, D.
    Vavrek, R.
    Wilson, C. D.
    Woodcraft, A.
    Initial highlights of the HOBYS key program, the Herschel imaging survey of OB young stellar objects2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 518, p. L77-Article in journal (Refereed)
    Abstract [en]

    We present the initial highlights of the HOBYS key program, which are based on Herschel images of the Rosette molecular complex and maps of the RCW120 H II region. Using both SPIRE at 250/350/500 mu m and PACS at 70/160 mu m or 100/160 mu m, the HOBYS survey provides an unbiased and complete census of intermediate-to high-mass young stellar objects, some of which are not detected by Spitzer. Key core properties, such as bolometric luminosity and mass (as derived from spectral energy distributions), are used to constrain their evolutionary stages. We identify a handful of high-mass prestellar cores and show that their lifetimes could be shorter in the Rosette molecular complex than in nearby low-mass star-forming regions. We also quantify the impact of expanding H II regions on the star formation process acting in both Rosette and RCW 120.

  • 55. Nilsson, R.
    et al.
    Brandeker, Alexis
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Fathi, Kambiz
    Stockholm University, Faculty of Science, Department of Astronomy.
    Thebault, Ph.
    Liseau, R.
    VLT imaging of the beta Pictoris gas disk2012In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 544, p. A134-Article in journal (Refereed)
    Abstract [en]

    Context. Circumstellar debris disks older than a few Myr should be largely devoid of primordial gas remaining from the protoplanetary disk phase. Tracing the origin of observed atomic gas in Keplerian rotation in the edge-on debris disk surrounding the similar to 12 Myr old star beta Pictoris requires more detailed information about its spatial distribution than has previously been acquired by limited slit spectroscopy. Especially indications of asymmetries and presence of Ca II gas at high disk latitudes call for additional investigation to exclude or confirm its connection to observed dust structures or suggested cometary bodies on inclined eccentric orbits. Aims. We set out to recover a complete image of the Fe I and Ca II gas emission around beta Pic by spatially resolved, high-resolution spectroscopic observations to better understand the morphology and origin of the gaseous disk component. Methods. The multiple fiber facility FLAMES/GIRAFFE at the Very Large Telescope (VLT), with the large integral-field-unit ARGUS, was used to obtain spatially resolved optical spectra (from 385.9 to 404.8 nm) in four regions covering the northeast and southwest side of the disk. Emission lines from Fe I (at 386.0 nm) and Ca II (at 393.4 and 396.8 nm) were mapped and could be used to fit a parametric function for the disk gas distribution, using a gas-ionisation code for gas-poor debris disks. Results. Both Fe I and Ca II emission are clearly detected, with the former dominating along the disk midplane, and the latter revealing vertically more extended gas. The surface intensity of the Fe I emission is lower but more extended in the northeast (reaching the 210 AU limit of our observations) than in the southwest, while Ca II shows the opposite asymmetry. The modelled Fe gas disk profile shows a linear increase in scale height with radius, and a vertical profile that suggests dynamical interaction with the dust. We also qualitatively demonstrate that the Ca II emission profile can be explained by optical thickness in the disk midplane, and does not require Ca to be spatially separated from Fe.

  • 56.
    Nilsson, Ricky
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Brandeker, Alexis
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Fathi, Kambiz
    Stockholm University, Faculty of Science, Department of Astronomy.
    Thébault, Philippe
    Liseau, René
    VLT imaging of the β Pictoris gas diskArticle in journal (Refereed)
  • 57.
    Nilsson, Ricky
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Liseau, René
    Brandeker, Alexis
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pilbratt, Göran
    Risacher, Christophe
    Rodmann, Jens
    Augereau, Jean-Charles
    Bergman, Per
    Eiroa, Carlos
    Fridlund, Malcolm
    Thébault, Philippe
    White, Glenn
    Kuiper belts around nearby stars2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 518, p. A40-Article in journal (Refereed)
    Abstract [en]

    Context. The existence of dusty debris disks around a large fraction of solar type main-sequence stars, inferred from excess far-IR and submillimetre emission compared to that expected from stellar photospheres, suggests that leftover planetesimal belts analogous to the asteroid-and comet reservoirs of the solar system are common.

    Aims. Sensitive submillimetre observations are essential to detect and characterise cold extended dust originating from collisions of small bodies in disks, belts, or rings at Kuiper-belt distances (30-50 AU or beyond). Measurements of the flux densities at these wavelengths will extend existing IR photometry and permit more detailed modelling of the Rayleigh-Jeans tail of the disks spectral energy distribution (SED), effectively constraining dust properties and disk extensions. By observing stars spanning from a few up to several hundred Myr, the evolution of debris disks during crucial phases of planet formation can be studied.

    Methods. We observed 22 exo-Kuiper-belt candidates at 870 mu m, as part of a large programme with the LABOCA bolometer at the APEX telescope. Dust masses (or upper limits) were calculated from integrated 870 mu m fluxes, and fits to the SED of detected sources revealed the fractional dust luminosities f(dust), dust temperatures T(dust), and power-law exponents beta of the opacity law.

    Results. A total of 10 detections with at least 3 sigma significance were made, out of which five (HD95086, HD131835, HD161868, HD170773, and HD207129) have previously never been detected at submillimetre wavelengths. Three additional sources are marginally detected with > 2.5 sigma significance. The best-fit beta parameters all lie between 0.1 and 0.8, in agreement with previous results indicating the presence of significantly larger grains than those in the ISM. From our relatively small sample we estimate f(dust) proportional to t(-alpha), with a similar to 0.8-2.0, and identify an evolution of the characteristic radial dust distance R(dust) that is consistent with the t(1/3) increase predicted from models of self-stirred collisions in debris disks.

  • 58.
    Nilsson, Ricky
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Liseau, René
    Brandeker, Alexis
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Risacher, Christophe
    Fridlund, Malcolm
    Pilbratt, Göran
    A submillimetre search for cold extended debris disks in the β Pictoris moving group2009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 508, no 2, p. 1057-1065Article in journal (Refereed)
    Abstract [en]

    Context. Previous observations with the Infrared Astronomical Satellite and the Infrared Space Observatory, and ongoing observations with Spitzer and AKARI, have led to the discovery of over 200 debris disks, based on detected mid-and far infrared excess emission, indicating warm circumstellar dust. To constrain the properties of these systems, e.g., to more accurately determine the dust mass, temperature and radial extent, follow-up observations in the submillimetre wavelength region are needed.

    Aims. The beta Pictoris moving group is a nearby stellar association of young (similar to 12 Myr) co-moving stars including the classical debris disk star beta Pictoris. Due to their proximity and youth, they are excellent targets when searching for submillimetre emission from cold, extended, dust components produced by collisions in Kuiper-Belt-like disks. They also allow an age independent study of debris disk properties as a function of other stellar parameters.

    Methods. We observed 7 infrared-excess stars in the beta Pictoris moving group with the LABOCA bolometer array, operating at a central wavelength of 870 mu m at the 12-m submillimetre telescope APEX. The main emission at these wavelengths comes from large, cold dust grains, which constitute the main part of the total dust mass, and hence, for an optically thin case, make better estimates on the total dust mass than earlier infrared observations. Fitting the spectral energy distribution with combined optical and infrared photometry gives information on the temperature and radial extent of the disk.

    Results. From our sample, beta Pic, HD181327, and HD172555 were detected with at least 3 sigma certainty, while all others are below 2 sigma and considered non-detections. The image of beta Pic shows an offset flux density peak located near the south-west extension of the disk, similar to the one previously found by SCUBA at the JCMT. We present SED fits for detected sources and give an upper limit on the dust mass for undetected ones.

    Conclusions. We find a mean fractional dust luminosity (f) over bar (dust) = 1.1 x 10(-3) at t approximate to 12 Myr, which together with recent data at 100 Myr suggests an f(dust) proportional to t(-alpha) a decline of the emitting dust, with alpha > 0.8.

  • 59. Olberg, M.
    et al.
    Frisk, U.
    Lecacheux, A.
    Olofsson, A. O. H.
    Baron, P.
    Bergman, P.
    Florin, G.
    Hjalmarson, Å..
    Larsson, B.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Murtagh, D.
    Olofsson, G.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pagani, L.
    Sandqvist, Aa.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Teyssier, D.
    Torchinsky, S. A.
    Volk, K.
    The Odin satellite. II. Radiometer data processing and calibration2003In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, p. L35-L38Article in journal (Refereed)
    Abstract [en]

    The radiometer on-board the Odin satellite comprises four different sub-mm receivers covering the 486-581 GHz frequency range and one fixed frequency 119 GHz receiver. Two auto-correlators and one acousto-optical spectrometer serve as backends. This article gives an overview over the processing of the data delivered by these instruments and discusses calibration issues. Odin is a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and the Centre National d'Études Spatiales (CNES, France). Odin is operated by the Swedish Space Corporation (SSC), the project's prime industrial contractor.

  • 60. Olofsson, A. O. H.
    et al.
    Olofsson, G.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Hjalmarson, Å.
    Bergman, P.
    Black, J. H.
    Booth, R. S.
    Buat, V.
    Curry, C. L.
    Encrenaz, P. J.
    Falgarone, E.
    Feldman, P.
    Fich, M.
    Florén, H. G.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Frisk, U.
    Gerin, M.
    Gregersen, E. M.
    Harju, J.
    Hasegawa, T.
    Johansson, L. E. B.
    Kwok, S.
    Larsson, B.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lecacheux, A.
    Liljeström, T.
    Liseau, R.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mattila, K.
    Mitchell, G. F.
    Nordh, H. L.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olberg, M.
    Olofsson, H.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pagani, L.
    Plume, R.
    Ristorcelli, I.
    Rydbeck, G.
    Sandqvist, Aa.
    Stockholm University, Faculty of Science, Department of Astronomy.
    von Schéele, F.
    Serra, G.
    Tothill, N. F.
    Volk, K.
    Wilson, C. D.
    Odin water mapping in the Orion KL region2003In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, p. L47-L54Article in journal (Refereed)
    Abstract [en]

    New results from water mapping observations of the Orion KL region using the submm/mm wave satellite Odin (2.1\arcmin beam size at 557 GHz), are presented. The ortho-H2O \jkktrans{1}{1}{0}{1}{0}{1} ground state transition was observed in a 7arcminx 7arcmin rectangular grid with a spacing of 1\arcmin, while the same line of H218O was measured in two positions, Orion KL itself and 2\arcmin south of Orion KL. In the main water species, the KL molecular outflow is largely resolved from the ambient cloud and it is found to have an extension of 60\arcsec-110\arcsec. The H2O outflow profile exhibits a rather striking absorption-like asymmetry at the line centre. Self-absorption in the near (or ``blue'') part of the outflow (and possibly in foreground quiescent halo gas) is tentatively suggested to play a role here. We argue that the dominant part of the KL H218O outflow emission emanates from the compact (size ~ 15\arcsec) low-velocity flow and here estimate an H2O abundance of circa 10-5 compared to all H2 in the flow - an order of magnitude below earlier estimates of the H2O abundance in the shocked gas of the high-velocity flow. The narrow ambient cloud lines show weak velocity trends, both in the N-S and E-W directions. H218O is detected for the first time in the southern position at a level of ~ 0.15 K and we here estimate an H2O abundance of (1-8) x 10-8. Odin is a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), and the Centre National d'Études Spatiales (CNES, France). The Swedish Space Corporation (SSC) was the industrial prime contractor and is also responsible for the satellite operation.

  • 61.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    GRB 090510: NOT afterglow confirmation.2009In: GRB Coordinates Network, Circular Service, no 9338, p. 1-Article in journal (Other academic)
  • 62.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    GRB081028 and its late-time afterglow re-brightening2010In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 402, no 1, p. 46-64Article in journal (Refereed)
    Abstract [en]

    Swift captured for the first time a smoothly rising X-ray re-brightening of clear non-flaring origin after the steep decay in a long gamma-ray burst (GRB): GRB081028. A rising phase is likely present in all GRBs but is usually hidden by the prompt tail emission and constitutes the first manifestation of what is later to give rise to the shallow decay phase. Contemporaneous optical observations reveal a rapid evolution of the injection frequency of a fast cooling synchrotron spectrum through the optical band, which disfavours the afterglow onset (start of the forward shock emission along our line of sight when the outflow is decelerated) as the origin of the observed re-brightening. We investigate alternative scenarios and find that the observations are consistent with the predictions for a narrow jet viewed off-axis. The high on-axis energy budget implied by this interpretation suggests different physical origins of the prompt and (late) afterglow emission. Strong spectral softening takes place from the prompt to the steep decay phase: we track the evolution of the spectral peak energy from the γ-rays to the X-rays and highlight the problems of the high latitude and adiabatic cooling interpretations. Notably, a softening of both the high and low spectral slopes with time is also observed. We discuss the low on-axis radiative efficiency of GRB081028 comparing its properties against a sample of Swift long GRBs with secure Eγ,iso measurements.

  • 63.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Recent Development Status of PoGOLitE2009In: Recent Development Status of PoGOLit, 2009, p. 386-Conference paper (Other academic)
  • 64.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    The SPIRE Instrument2009In: EAS Publications Series, Vol. 34, p. 33-42Article in journal (Other academic)
    Abstract [en]

    SPIRE, the Spectral and Photometric Imaging Receiver, is Herschel's submillimetre camera and spectrometer. It comprises a three-band imaging photometer operating at 250, 350 and 500 µm, and an imaging Fourier Transform Spectrometer (FTS) covering 194–672 µm. The design of SPIRE is described, and the expected scientific performance is summarised, based on modelling and flight instrument test results.

  • 65.
    Olofsson, Göran
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Fyndbo, J.P.U.
    Jakobsson, P.
    GRB 081028: optical observations at the NOT.2008Report (Other academic)
  • 66.
    Olofsson, Göran
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Nilsson, R.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Florén, Hans-Gustav
    Stockholm University, Faculty of Science, Department of Astronomy.
    Djupvik, A.
    Aberasturi, M.
    Polarimetric coronagraphy of BD+31 degrees 6432012In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 544, p. A43-Article in journal (Refereed)
    Abstract [en]

    Context. The binary B5V star BD+ 31 degrees 643 exhibits a disk-like structure detected at optical wavelengths. Even though the feature is well centered on the star, it has been argued, based on Spitzer observations, that the feature is a filament not directly associated to the binary star. Aims. The purpose of the present paper is to investigate whether polarization imaging may provide evidence either for or against the disk hypothesis. In addition, we aim at clarifying whether there might be any additional close companion to the binary star. Methods. We used the coronagraph PolCor in its polarization mode in combination with an EMCCD camera allowing short unit exposure times. As a result of shift-and-add and frame selection, the spatial resolution is improved compared to traditional CCD imaging. In order to possibly reveal an additional stellar companion, we used high resolution spectroscopy in the optical and high spatial resolution imaging in the near-IR. Results. The disk/filament is much better seen in polarization; it is narrow and a line drawn along the ridge passes within a second of arc from the star. The degree of polarization is high (approximate to 50% after correction for the extended component of the reflection nebula) which means that the disk/filament must be approximately at the same distance as the star. Although we confirm that the feature is much brighter south-east than north-west of the star, the evidence that the feature is physically connected to the star is strengthened and suggests that we are witnessing the destruction process of an accretion disk. Our spectroscopy shows that at least one of the stars is a spectroscopic binary. We were, however, not able to spatially resolve any stellar component in addition to the two well separated stars.

  • 67.
    Olofsson, Göran
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Nilsson, Ricky
    Stockholm University, Faculty of Science, Department of Astronomy.
    Florén, Hans-Gustav
    Stockholm University, Faculty of Science, Department of Astronomy.
    Djupvik, Amanda
    Aberasturi, M.
    Polarimetric coronagraphy of BD+31°643Article in journal (Refereed)
  • 68.
    Olofsson, Sven
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    A new method of determining distances to dark globules.: The distance to B 3352009In: Astronomy & Astrophysics, Vol. 498, no 2, p. 455-461Article in journal (Refereed)
    Abstract [en]

    Context. The distance to an isolated dark globule is often unknown and yet crucial for understanding its properties, in particular its mass. A new approach to this problem is discussedAims. The purpose of the present paper is to investigate how well the distances of more or less reddened field stars can be determined by using multi-colour imaging.Methods. We observed a test globule, B 335 in UBgr, and I, and together with the 2MASS survey, this data set gives a well-defined spectral energy distribution (SED) of a large number of stars. The SED of each star depends on the interstellar extinction, the distance to the star, and its intrinsic SED. As we had good reasons to suspect that the wavelength dependence of the extinction (the reddening) changes from the outskirts of the globule to the central parts, we did not assume any specific reddening law. Instead, we use a scheme that allows independent determination of the extinction in each line of sight as determined by groups of adjacent stars. The method is based on the use of stellar atmospheric models to represent the intrinsic SEDs of the stars. Formally, it is then possible to determine the spectral class of each star and thereby its distance. For some of the stars we have optical spectra, allowing us to compare the photometric classification to the spectrometric. Results. As expected, the main problem is that there are few stars found within each distance bin for the small field size defining a typical dark globule. However, the characterisation of the extinction and photometric classification give consistent results and we can identify one star at the front side of the globule. It has a photometric distance of 90 pc. The closest star behind the B 335 globule has a distance of only 120 pc and we therefore determine the distance to B 335 as 90-120 pc. Our deep U image shows a relatively bright south-western rim of the globule, and we investigate whether it might be due to a local enhancement of the radiation field. A candidate source, located 1.5 arcmin outside our field, would be the field star, HD 184982. This star has an entry in the Hipparcos Catalogue and its distance is 140-200 pc. However, we come to the conclusion that the bright SW rim is more likely due to the wing of the point-spread-function (PSF) of this star.

  • 69.
    Olofsson, Sven
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    The extinction law for molecular clouds Case study of B3352010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 522, p. A84-Article in journal (Refereed)
    Abstract [en]

    Context. The large optical and near-IR surveys have made it possible to investigate the properties of dark clouds by means of extinction estimates. There is, however, a need for case studies in more detail in order to investigate the basic assumptions when, say, interpreting reddening in terms of column density. Aims. We determine the extinction curve from the UV to the near-IR for molecular clouds and investigate whether current models can adequately explain this wavelength dependence of the extinction. The aim is also to interpret the extinction in terms of H-2 column density. Methods. We applied five different methods, including a new method for simultaneously determining the reddening law and the classification of the background stars. Our method is based on multicolour observations and a grid of model atmospheres. Results. We confirm that the extinction law can be adequately described by a single parameter, R-V (the selective to absolute extinction), in accordance with earlier findings. The R-V value for B335 is R-V = 4.8. The reddening curve can be accurately reproduced by model calculations. By assuming that all the silicon is bound in silicate grains, we can interpret the reddening in terms of column density, N-H = 4.4 (+/- 0.5) x 10(21) EI-Ks cm(-2), corresponding to N-H = 2.3 (+/- 0.2) x 10(21) . AV cm(-2), close to that of the diffuse ISM, (1.8-2.2) x 10(21) cm(-2). We show that the density of the B335 globule outer shells can be modelled as an evolved Ebert-Bonnor gas sphere with.. rho proportional to r(2), and estimate the mass of this globule to 2.5 M-circle dot

  • 70.
    Olofsson, Sven
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    The mid-infrared extinction in molecular clouds: Case study of B 3352011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 534, p. A127-Article in journal (Refereed)
    Abstract [en]

     Field stars behind a molecular cloud can be used to probe the cloud extinction for both the reddening and the absorption features. By combining multi-colour photometry and IR spectroscopy the spectral class of the star can be determined as can the extinction curve, including the vibrational bands of ices and silicates. Results. Based on observations of field stars behind the dark globule B335, we determine the reddening curve from 0.35 to 24 mu m. The water ice band at 3.1 mu m is weaker (tau(3.1) = 0.4) than expected from the cloud extinction (A(V) approximate to 10 for the sightline to the most obscured star). On the other hand, the CO ice band at 4.7 mu m is strong (tau(4.67) = 0.7) and indicates that the mass column density of frozen CO is about the same as that of water ice. We fit the observations to model calculations and find that the thin ice coatings on the silicate and carbon grains (assumed to be spherical) lower the optical extinction by a few percent. We show that the reddening curves for the two background stars, for which the silicate band has been measured, can be accurately modelled from the UV to 24 mu m. These models only include graphite and silicate grains (plus thin ice mantles for the most obscured star), so there is no need for any additional major grain component to explain the slow decline of the reddening curve beyond the K band. As expected, the dust model for the dense part of the cloud has more large grains than for the outer regions. We propose that the well established shallow reddening curve beyond the K band has two different explanations: larger graphite grains in dense regions and relatively small grains in the diffuse ISM, giving rise to substantially less extinction beyond the K band than previously thought. Conclusions. For the sight line towards the most obscured star, we derive the relation A(Ks) = 0.97 . E(J - K(Ks)), and assuming that all silicon is bound in silicates, N(2H(2)+H) approximate to 1.5 x 10(21) . A(V) approximate to 9 x 10(21) . A(Ks). For the rim of the cloud we get A(Ks) = 0.51 . E(J -K(s)), which is close to recent determinations for the diffuse ISM. The corresponding gas column density is N(2H(2)+H) approximate to 2.3 x 10(21) . A(V) approximate to 3 x 10(22) . A(Ks).

  • 71. Pagani, L.
    et al.
    Olofsson, A. O. H.
    Bergman, P.
    Bernath, P.
    Black, J. H.
    Booth, R. S.
    Buat, V.
    Crovisier, J.
    Curry, C. L.
    Encrenaz, P. J.
    Falgarone, E.
    Feldman, P. A.
    Fich, M.
    Floren, H. G.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Frisk, U.
    Gerin, M.
    Gregersen, E. M.
    Harju, J.
    Hasegawa, T.
    Hjalmarson, Å.
    Johansson, L. E. B.
    Kwok, S.
    Larsson, B.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lecacheux, A.
    Liljeström, T.
    Lindqvist, M.
    Liseau, R.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mattila, K.
    Mitchell, G. F.
    Nordh, L. H.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olberg, M.
    Olofsson, G.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Ristorcelli, I.
    Sandqvist, Aa.
    Stockholm University, Faculty of Science, Department of Astronomy.
    von Scheele, F.
    Serra, G.
    Tothill, N. F.
    Volk, K.
    Wiklind, T.
    Wilson, C. D.
    Low upper limits on the O2 abundance from the Odin satellite2003In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, p. L77-L81Article in journal (Refereed)
    Abstract [en]

    For the first time, a search has been conducted in our Galaxy for the 119 GHz transition connecting to the ground state of O2, using the Odin satellite. Equipped with a sensitive 3 mm receiver (Tsys(SSB) = 600 K), Odin has reached unprecedented upper limits on the abundance of O2, especially in cold dark clouds where the excited state levels involved in the 487 GHz transition are not expected to be significantly populated. Here we report upper limits for a dozen sources. In cold dark clouds we improve upon the published SWAS upper limits by more than an order of magnitude, reaching N(O2)/N(H2) <= 10-7 in half of the sources. While standard chemical models are definitively ruled out by these new limits, our results are compatible with several recent studies that derive lower O2 abundances. Goldsmith et al. (\cite{SWAS2002}) recently reported a SWAS tentative detection of the 487 GHz transition of O2 in an outflow wing towards rho Oph A in a combination of 7 beams covering approximately 10arcmin x 14arcmin . In a brief (1.3 hour integration time) and partial covering of the SWAS region (~65% if we exclude their central position), we did not detect the corresponding 119 GHz line. Our 3 sigma upper limit on the O2 column density is 7.3x 1015 cm-2. We presently cannot exclude the possibility that the SWAS signal lies mostly outside of the 9\arcmin Odin beam and has escaped our sensitive detector. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation was the industrial prime contractor and is operating Odin.

  • 72. Ramstedt, S.
    et al.
    Maercker, M.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olofsson, H.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Schoier, F. L.
    Imaging the circumstellar dust around AGB stars with PolCor2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 531, p. A148-Article in journal (Refereed)
    Abstract [en]

    Aims. The aim of this paper is to investigate how the new imaging Polarimeter and Coronograph (PolCor) at the Nordic Optical Telescope** (NOT) can be used in the study of circumstellar structures around AGB stars. The purpose is to prepare for a study of a larger sample. Methods. We have observed two types of AGB stars using the PolCor instrument on the NOT: the binary S-type star W Aql and two carbon stars with detached shells, U Cam and DR Ser. The polarized light traces the dust distribution around the stars. From the polarimeter images the polarized intensity, the polarization degree, and the polarization angle over the images are calculated. The location and extent of dust structures are examined in the images. The total dust mass and the dust-to-gas ratios of the detached shells are also calculated. Results. The images of the circumstellar envelope of W Aql show what seems to be an elongated structure in the south-west direction. The detached shells of U Cam and DR Ser are clearly seen in the images. This is the first time the detached shell around DR Ser has been imaged. The radii (R(sh)) and widths (Delta R(sh)) of the shells are determined and found to be R(sh) = 7 ''.9 and 7 ''.6, and Delta R(sh) = 0 ''.9 and 1 ''.2, for U Cam and DR Ser, respectively. This is consistent with previous results. The dust masses of the feature south-west of W Aql, and in the shells of U Cam and DR Ser are also estimated and found to be 1 x 10(-6), 5 x 10(-7), and 2 x 10(-6) M(circle dot), respectively. Conclusions. W Aql is a known binary and the shape of the circumstellar envelope seems to be in line with what could be expected from binary interaction on these scales. For the shells, the results are in agreement with previous investigations. Ages and formation time-scales are also estimated for the detached shells and found to be consistent with the thermal-pulse-formation scenario.

  • 73. Regibo, S.
    et al.
    Vandenbussche, B.
    Waelkens, C.
    Acke, B.
    Sibthorpe, B.
    Nottebaere, M.
    Voet, K.
    Di Francesco, J.
    Fridlund, M.
    Gear, W. K.
    Ivison, R. J.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    A background galaxy in the field of the beta Pictoris debris disk2012In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 541, p. A3-Article in journal (Refereed)
    Abstract [en]

    Herschel images in six photometric bands show the thermal emission of the debris disk surrounding beta Pic. In the three PACS bands at 70 mu m, 100 mu m and 160 mu m and in the 250 mu m SPIRE band, the disk is well-resolved, and additional photometry is available in the SPIRE bands at 350 mu m and 500 mu m, where the disk is only marginally resolved. The SPIRE maps reveal a blob to the southwest of beta Pic, coinciding with submillimetre detection of excess emission in the disk. We investigated the nature of this blob. Our comparison of the colours, spectral energy distribution and size of the blob, the disk and the background sources shows that the blob is most likely a background source with a redshift between z = 1.0 and z = 1.6.

  • 74. Royer, P.
    et al.
    Decin, L.
    Wesson, R.
    Barlow, M. J.
    Polehampton, E. T.
    Matsuura, M.
    Agundez, M.
    Blommaert, J. A. D. L.
    Cernicharo, J.
    Cohen, M.
    Daniel, F.
    Degroote, P.
    De Meester, W.
    Exter, K.
    Feuchtgruber, H.
    Gear, W. K.
    Gomez, H. L.
    Groenewegen, M. A. T.
    Hargrave, P. C.
    Huygen, R.
    Imhof, P.
    Ivison, R. J.
    Jean, C.
    Kerschbaum, F.
    Leeks, S. J.
    Lim, T.
    Lombaert, R.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Posch, T.
    Regibo, S.
    Savini, G.
    Sibthorpe, B.
    Swinyard, B. M.
    Vandenbussche, B.
    Waelkens, C.
    Witherick, D. K.
    Yates, J. A.
    PACS and SPIRE spectroscopy of the red supergiant VY CMa2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 518, p. L145-Article in journal (Refereed)
    Abstract [en]

    With a luminosity > 10(5) L-circle dot and a mass-loss rate of similar to 2 x 10(-4) M-circle dot yr(-1), the red supergiant VY CMa truly is a spectacular object. Because of its extreme evolutionary state, it could explode as supernova any time. Studying its circumstellar material, into which the supernova blast will run, provides interesting constraints on supernova explosions and on the rich chemistry taking place in such complex circumstellar envelopes. We have obtained spectroscopy of VY CMa over the full wavelength range offered by the PACS and SPIRE instruments of Herschel, i.e. 55-672 micron. The observations show the spectral fingerprints of more than 900 spectral lines, of which more than half belong to water. In total, we have identified 13 different molecules and some of their isotopologues. A first analysis shows that water is abundantly present, with an ortho-to-para ratio as low as similar to 1.3:1, and that chemical non-equilibrium processes determine the abundance fractions in the inner envelope.

  • 75. Sandin, Christer
    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).
    Lundqvist, Natallia
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Björnsson, Claes-Ingvar
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Shibanov, Yuri A.
    Properties of the three-dimensional structure in the central region of the supernova remnant SNR 0540−69.32013In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 432, no 4, p. 2854-2868Article in journal (Refereed)
    Abstract [en]

    We present and discuss new visual wavelength-range observations of the inner regions of the supernova remnant SNR 0540−69.3 that is located in the Large Magellanic Cloud (LMC). These observations provide us with more spatial and spectral information than were previously available for this object. We use these data to create a detailed three-dimensional model of the remnant, assuming linear expansion of the ejecta. With the observations and the model, we study the general three-dimensional structure of the remnant, and the influence of an active region in the remnant – a ‘blob’ – that we address in previous papers. We used the fibre-fed integral-field Visual Multi-Object Spectrograph at the Very Large Telescope of the European Southern Observatory. The observations provide us with three-dimensional data in [O iii] λ5007 and [S ii] λλ6717, 6731 at a 0.33 arcsec × 0.33 arcsec spatial sampling and a velocity resolution of about 35 km s− 1. We decomposed the two, partially overlapping, sulphur lines and used them to calculate electron densities across the remnant at a high signal-to-noise ratio. In our study, we recover results of previous studies, but we are more importantly able to obtain more detailed information than before. Our analysis reveals a structure that stretches from the position of the ‘blob’, and into the plane of the sky at a position angle of PA ≃ 60°. Assuming a remnant age of 1000 yr and the usual LMC distance, the structure has an inclination angle of about 65° to the line of sight. The position angle is close to the symmetry axis with present and past activity in the visual and the X-ray wavelength ranges. We speculate that the pulsar is positioned along this activity axis, where it has a velocity along the line of sight of a few hundred  km s− 1. The ‘blob’ is most likely a region of shock activity, as it is mainly bright in [S ii]; future observations of [O ii] λλ3726, 3729 would be useful to test whether the S/O abundance ratio is higher than average for that location in the remnant. The striking resemblance in X-rays between the pulsar wind nebula (PWN) of SNR 0540−69.3 and the Crab, in combination with our findings in this paper, suggests that the symmetry axis is part of a torus in the PWN. This is in agreement with the original suggestion by Gotthelf & Wang.

  • 76.
    Sandqvist, Aa.
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Bergman, P.
    Black, J. H.
    Booth, R.
    Buat, V.
    Curry, C. L.
    Encrenaz, P.
    Falgarone, E.
    Feldman, P.
    Fich, M.
    Floren, H. G.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Frisk, U.
    Gerin, M.
    Gregersen, E. M.
    Harju, J.
    Hasegawa, T.
    Hjalmarson, Å.
    Johansson, L. E. B.
    Kwok, S.
    Larsson, B.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lecacheux, A.
    Liljeström, T.
    Lindqvist, M.
    Liseau, R.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mattila, K.
    Mitchell, G. F.
    Nordh, L.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olberg, M.
    Olofsson, A. O. H.
    Olofsson, G.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pagani, L.
    Plume, R.
    Ristorcelli, I.
    Schéele, F. v.
    Serra, G.
    Tothill, N. F. H.
    Volk, K.
    Wilson, C. D.
    Winnberg, A.
    Odin observations of H2O in the Galactic Centre2003In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, p. L63-L67Article in journal (Refereed)
    Abstract [en]

    The Odin satellite has been used to detect emission and absorption in the 557-GHz H216O line in the Galactic Centre towards the Sgr Astar Circumnuclear Disk (CND), and the Sgr A +20 km s-1 and +50 km s-1 molecular clouds. Strong broad H2O emission lines have been detected in all three objects. Narrow H2O absorption lines are present at all three positions and originate along the lines of sight in the 3-kpc Spiral Arm, the -30 km s-1 Spiral Arm and the Local Sgr Spiral Arm. Broad H2O absorption lines near -130 km s-1 are also observed, originating in the Expanding Molecular Ring. A new molecular feature (the ``High Positive Velocity Gas'' - HPVG) has been identified in the positive velocity range of ~+120 to +220 km s-1, seen definitely in absorption against the stronger dust continuum emission from the +20 km s-1 and +50 km s-1 clouds and possibly in emission towards the position of Sgr Astar CND. The 548-GHz H218O isotope line towards the CND is not detected at the 0.02 K (rms) level. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation was the industrial prime contractor and is also responsible for the satellite operation.

  • 77.
    Sandqvist, Aage
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Hjalmarson, A.
    Frisk, U.
    Lundin, S.
    Nordh, L.
    Stockholm Univ, AlbaNova Univ Ctr, Stockholm Observ, S-10691 Stockholm, Sweden.
    Olberg, M.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Odin observations of ammonia in the SgrA+50 km s(-1) cloud and circumnuclear disk2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 599, article id A135Article in journal (Refereed)
    Abstract [en]

    Context. The Odin satellite is now into its sixteenth year of operation, much surpassing its design life of two years. One of the sources which Odin has observed in great detail is the Sgr A complex in the centre of the Milky Way.

    Aims. To study the presence of NH3 in the Galactic centre and spiral arms.

    Methods. Recently, Odin has made complementary observations of the 572 GHz NH3 line towards the SgrA + 50 km s(-1) cloud and circumnuclear disk (CND).

    Results. Significant NH3 emission has been observed in both the + 50 km s(-1) cloud and the CND. Clear NH3 absorption has also been detected in many of the spiral arm features along the line of sight from the Sun to the core of our Galaxy.

    Conclusions. The very large velocity width (80 km s 1) of the NH3 emission associated with the shock region in the southwestern part of the CND may suggest a formation / desorption scenario similar to that of gas-phase H2O in shocks / outflows.

  • 78. Schneider, N.
    et al.
    Motte, F.
    Bontemps, S.
    Hennemann, M.
    Di Francesco, J.
    Andre, Ph.
    Zavagno, A.
    Csengeri, T.
    Men'shchikov, A.
    Abergel, A.
    Baluteau, J. -P
    Bernard, J. -Ph.
    Cox, P.
    Didelon, P.
    di Giorgio, A. -M
    Gastaud, R.
    Griffin, M.
    Hargrave, P.
    Hill, T.
    Huang, M.
    Kirk, J.
    Koenyves, V.
    Leeks, S.
    Li, J. Z.
    Marston, A.
    Martin, P.
    Minier, V.
    Molinari, S.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Panuzzo, P.
    Persi, P.
    Pezzuto, S.
    Roussel, H.
    Russeil, D.
    Sadavoy, S.
    Saraceno, P.
    Sauvage, M.
    Sibthorpe, B.
    Spinoglio, L.
    Testi, L.
    Teyssier, D.
    Vavrek, R.
    Ward-Thompson, D.
    White, G.
    Wilson, C. D.
    Woodcraft, A.
    The Herschel view of star formation in the Rosette molecular cloud under the influence of NGC 22442010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 518, p. L83-Article in journal (Refereed)
    Abstract [en]

    Context. The Rosette molecular cloud is promoted as the archetype of a triggered star-formation site. This is mainly due to its morphology, because the central OB cluster NGC 2244 has blown a circular-shaped cavity into the cloud and the expanding H II-region now interacts with the cloud. Aims. Studying the spatial distribution of the different evolutionary states of all star-forming sites in Rosette and investigating possible gradients of the dust temperature will help to test the "triggered star-formation" scenario in Rosette. Methods. We use continuum data obtained with the PACS (70 and 160 mu m) and SPIRE instruments (250, 350, 500 mu m) of the Herschel telescope during the science demonstration phase of HOBYS. Results. Three-color images of Rosette impressively show how the molecular gas is heated by the radiative impact of the NGC 2244 cluster. A clear negative temperature gradient and a positive density gradient (running from the H II-region/molecular cloud interface into the cloud) are detected. Studying the spatial distribution of the most massive dense cores (size scale 0.05 to 0.3 pc), we find an age-sequence (from more evolved to younger) with increasing distance to the cluster NGC 2244. No clear gradient is found for the clump (size-scale up to 1 pc) distribution. Conclusions. The existence of temperature and density gradients and the observed age-sequence imply that star formation in Rosette may indeed be influenced by the radiative impact of the central NGC 2244 cluster. A more complete overview of the prestellar and protostellar population in Rosette is required to obtain a firmer result.

  • 79. Sibthorpe, B.
    et al.
    Vandenbussche, B.
    Greaves, J. S.
    Pantin, E.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Acke, B.
    Barlow, M. J.
    Blommaert, J. A. D. L.
    Bouwman, J.
    Brandeker, Alexis
    Stockholm University, Faculty of Science, Department of Astronomy.
    Cohen, M.
    De Meester, W.
    Dent, W. R. F.
    Di Francesco, J.
    Dominik, C.
    Fridlund, M.
    Gear, W. K.
    Glauser, A. M.
    Gomez, H. L.
    Hargrave, P. C.
    Harvey, P. M.
    Henning, Th.
    Heras, A. M.
    Hogerheijde, M. R.
    Holland, W. S.
    Ivison, R. J.
    Leeks, S. J.
    Lim, T. L.
    Liseau, R.
    Matthews, B. C.
    Naylor, D. A.
    Pilbratt, G. L.
    Polehampton, E. T.
    Regibo, S.
    Royer, P.
    Sicilia-Aguilar, A.
    Swinyard, B. M.
    Waelkens, C.
    Walker, H. J.
    Wesson, R.
    The Vega debris disc: A view from Herschel2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 518, p. L130-Article in journal (Refereed)
    Abstract [en]

    We present five band imaging of the Vega debris disc obtained using the Herschel Space Observatory. These data span a wavelength range of 70-500 mu m with full-width half-maximum angular resolutions of 5.6-36.9 ''. The disc is well resolved in all bands, with the ring structure visible at 70 and 160 mu m. Radial profiles of the disc surface brightness are produced, and a disc radius of 11 '' (similar to 85AU) is determined. The disc is seen to have a smooth structure thoughout the entire wavelength range, suggesting that the disc is in a steady state, rather than being an ephemeral structure caused by the recent collision of two large planetesimals.

  • 80. Van de Steene, G. C.
    et al.
    van Hoof, P. A. M.
    Exter, K. M.
    Barlow, M. J.
    Cernicharo, J.
    Etxaluze, M.
    Gear, W. K.
    Goicoechea, J. R.
    Gomez, H. L.
    Groenewegen, M. A. T.
    Hargrave, P. C.
    Ivison, R. J.
    Leeks, S. J.
    Lim, T. L.
    Matsuura, M.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Polehampton, E. T.
    Swinyard, B. M.
    Ueta, T.
    Van Winckel, H.
    Waelkens, C.
    Wesson, R.
    Herschel imaging of the dust in the Helix nebula (NGC 7293)2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 574, article id A134Article in journal (Refereed)
    Abstract [en]

    Aims. In our series of papers presenting the Herschel imaging of evolved planetary nebulae, we present images of the dust distribution in the Helix nebula (NGC 7293). Methods. Images at 70, 160, 250, 350, and 500 mu m were obtained with the PACS and SPIRE instruments on board the Herschel satellite. Results. The broadband maps show the dust distribution over the main Helix nebula to be u npy and predominantly present in the barrel wall. We determined the spectral energy distribution of the main nebula in a consistent way using Herschel. IRAS. and Planck flux values, The emissivity index of beta = 0.99 +/- 0.09, in combination with the carbon rich molecular chemistry of the nebula, indicates that the dust consists mainly of amorphous carbon. The dust excess emission from the central star disk is detected at 70 pm and the flux measurement agrees with previous measurement. We present the temperature and dust column density maps. The total dust mass across the Helix nebula (without its halo) is determined to be 3.5 x 10(-3) M-circle dot at a distance of 216 pc. The temperature map shows dust temperatures between 22 K and 42 K, which is similar to the kinetic temperature of the molecular gas, confirming that the dust and gas co exist in high density clumps. Archived images are used to compare the location of the dust emission in the far infrared (Herschel) with the ionized (GALEX and H-beta) and molecular (H-2) component. The different emission components are consistent with the Helix consisting of a thick walled barrel-like structure inclined to the line of sight. The radiation field decreases rapidly through the barrel wall.

  • 81. van der Wiel, M. H. D.
    et al.
    Naylor, D. A.
    Kamp, I.
    Menard, F.
    Thi, W-F
    Woitke, P.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pontoppidan, K. M.
    Di Francesco, J.
    Glauser, A. M.
    Greaves, J. S.
    Ivison, R. J.
    Signatures of warm carbon monoxide in protoplanetary discs observed with Herschel SPIRE2014In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 444, no 4, p. 3911-3925Article in journal (Refereed)
    Abstract [en]

    Molecular gas constitutes the dominant mass component of protoplanetary discs. To date, these sources have not been studied comprehensively at the longest far-infrared and shortest submillimetre wavelengths. This paper presents Herschel SPIRE FTS spectroscopic observations towards 18 protoplanetary discs, covering the entire 450-1540 GHz (666-195 mu m) range at upsilon/Delta upsilon approximate to 400-1300. The spectra reveal clear detections of the dust continuum and, in six targets, a significant amount of spectral line emission primarily attributable to (CO)-C-12 rotational lines. Other targets exhibit little to no detectable spectral lines. Low signal-to-noise detections also include signatures from (CO)-C-13, [C I] and HCN. For completeness, we present upper limits of non-detected lines in all targets, including low-energy transitions of H2O and CH+ molecules. The 10 (CO)-C-12 lines that fall within the SPIRE FTS bands trace energy levels of similar to 50-500 K. Combined with lower and higher energy lines from the literature, we compare the CO rotational line energy distribution with detailed physical-chemical models, for sources where these are available and published. Our (CO)-C-13 line detections in the disc around Herbig Be star HD 100546 exceed, by factors of similar to 10-30, the values predicted by a model that matches a wealth of other observational constraints, including the SPIRE (CO)-C-12 ladder. To explain the observed (CO)-C-12/(CO)-C-13 ratio, it may be necessary to consider the combined effects of optical depth and isotope selective (photo) chemical processes. Considering the full sample of 18 objects, we find that the strongest line emission is observed in discs around Herbig Ae/Be stars, although not all show line emission. In addition, two of the six T Tauri objects exhibit detectable (CO)-C-12 lines in the SPIRE range.

  • 82. van Hoof, P. A. M.
    et al.
    Van de Steene, G. C.
    Barlow, M. J.
    Exter, K. M.
    Sibthorpe, B.
    Ueta, T.
    Peris, V.
    Groenewegen, M. A. T.
    Blommaert, J. A. D. L.
    Cohen, M.
    De Meester, W.
    Ferland, G. J.
    Gear, W. K.
    Gomez, H. L.
    Hargrave, P. C.
    Huygen, E.
    Ivison, R. J.
    Jean, C.
    Leeks, S. J.
    Lim, T. L.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Polehampton, E. T.
    Regibo, S.
    Royer, P.
    Swinyard, B. M.
    Vandenbussche, B.
    Van Winckel, H.
    Waelkens, C.
    Walker, H. J.
    Wesson, R.
    Herschel images of NGC 6720: H-2 formation on dust grains2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 518, p. L137-Article in journal (Refereed)
    Abstract [en]

    Herschel PACS and SPIRE images have been obtained of NGC 6720 (the Ring nebula). This is an evolved planetary nebula with a central star that is currently on the cooling track, due to which the outer parts of the nebula are recombining. From the PACS and SPIRE images we conclude that there is a striking resemblance between the dust distribution and the H-2 emission, which appears to be observational evidence that H-2 forms on grain surfaces. We have developed a photoionization model of the nebula with the Cloudy code which we used to determine the physical conditions of the dust and investigate possible formation scenarios for the H-2. We conclude that the most plausible scenario is that the H-2 resides in high density knots which were formed after the recombination of the gas started when the central star entered the cooling track. Hydrodynamical instabilities due to the unusually low temperature of the recombining gas are proposed as a mechanism for forming the knots. H-2 formation in the knots is expected to be substantial after the central star underwent a strong drop in luminosity about one to two thousand years ago, and may still be ongoing at this moment, depending on the density of the knots and the properties of the grains in the knots.

  • 83. van Hoof, P. A. M.
    et al.
    Van de Steene, G. C.
    Exter, K. M.
    Barlow, M. J.
    Ueta, T.
    Groenewegen, M. A. T.
    Gear, W. K.
    Gomez, H. L.
    Hargrave, P. C.
    Ivison, R. J.
    Leeks, S. J.
    Lim, T. L.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Polehampton, E. T.
    Swinyard, B. M.
    Van Winckel, H.
    Waelkens, C.
    Wesson, R.
    A Herschel study of NGC 6502013In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 560, p. A7-Article in journal (Refereed)
    Abstract [en]

    As part of the Herschel guaranteed time key project Mass loss of Evolved StarS (MESS) we have imaged a sample of planetary nebulae. In this paper we present the Photodetector Array Camera and Spectrometer (PACS) and Spectral and Photometric Imaging Receiver (SPIRE) images of the classical bipolar planetary nebula NGC 650. We used these images to derive a temperature map of the dust. We also constructed a photoionization and dust radiative transfer model using the spectral synthesis code Cloudy. To constrain this model, we used the PACS and SPIRE fluxes and combined them with hitherto unpublished International Ultraviolet Explorer (IUE) and Spitzer InfraRed Spectrograph (IRS) spectra as well as various other data from the literature. A temperature map combined with a photoionization model were used to study various aspects of the central star, the nebula, and in particular the dust grains in the nebula. The central star parameters are determined to be T-eff = 208 kK and L = 261 L-circle dot assuming a distance of 1200 pc. The stellar temperature is much higher than previously published values. We confirm that the nebula is carbon-rich with a C/O ratio of 2.1. The nebular abundances are typical for a type IIa planetary nebula. With the photoionization model we determined that the grains in the ionized nebula are large (assuming single-sized grains, they would have a radius of 0.15 mu m). Most likely these large grains were inherited from the asymptotic giant branch phase. The PACS 70/160 mu m temperature map shows evidence of two radiation components heating the grains. The first component is direct emission from the central star, while the second component is diffuse emission from the ionized gas (mainly Ly alpha). We show that previous suggestions of a photo-dissociation region surrounding the ionized region are incorrect. The neutral material resides in dense clumps inside the ionized region. These may also harbor stochastically heated very small grains in addition to the large grains.

  • 84. Vandenbussche, B.
    et al.
    Sibthorpe, B.
    Acke, B.
    Pantin, E.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Waelkens, C.
    Dominik, C.
    Barlow, M. J.
    Blommaert, J. A. D. L.
    Bouwman, J.
    Brandeker, Alexis
    Stockholm University, Faculty of Science, Department of Astronomy.
    Cohen, M.
    De Meester, W.
    Dent, W. R. F.
    Exter, K.
    Di Francesco, J.
    Fridlund, M.
    Gear, W. K.
    Glauser, A. M.
    Gomez, H. L.
    Greaves, J. S.
    Hargrave, P. C.
    Harvey, P. M.
    Henning, Th.
    Heras, A. M.
    Hogerheijde, M. R.
    Holland, W. S.
    Huygen, R.
    Ivison, R. J.
    Jean, C.
    Leeks, S. J.
    Lim, T. L.
    Liseau, R.
    Matthews, B. C.
    Naylor, D. A.
    Pilbratt, G. L.
    Polehampton, E. T.
    Regibo, S.
    Royer, P.
    Sicilia-Aguilar, A.
    Swinyard, B. M.
    Walker, H. J.
    Wesson, R.
    The beta Pictoris disk imaged by Herschel PACS and SPIRE2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 518, p. L133-Article in journal (Refereed)
    Abstract [en]

    We obtained Herschel PACS and SPIRE images of the thermal emission of the debris disk around the A5V star beta Pic. The disk is well resolved in the PACS filters at 70, 100, and 160 mu m. The surface brightness profiles between 70 and 160 mu m show no significant asymmetries along the disk, and are compatible with 90% of the emission between 70 and 160 mu m originating in a region closer than 200 AU to the star. Although only marginally resolving the debris disk, the maps obtained in the SPIRE 250-500 mu m filters provide full-disk photometry, completing the SED over a few octaves in wavelength that had been previously inaccessible. The small far-infrared spectral index (beta = 0.34) indicates that the grain size distribution in the inner disk (<200 AU) is inconsistent with a local collisional equilibrium. The size distribution is either modified by non-equilibrium effects, or exhibits a wavy pattern, caused by an under-abundance of impactors which have been removed by radiation pressure.

  • 85. Ward-Thompson, D.
    et al.
    Kirk, J. M.
    Andre, P.
    Saraceno, P.
    Didelon, P.
    Koenyves, V.
    Schneider, N.
    Abergel, A.
    Baluteau, J. -P
    Bernard, J. -Ph.
    Bontemps, S.
    Cambresy, L.
    Cox, P.
    Di Francesco, J.
    Di Giorgio, A. M.
    Griffin, M.
    Hargrave, P.
    Huang, M.
    Li, J. Z.
    Martin, P.
    Men'shchikov, A.
    Minier, V.
    Molinari, S.
    Motte, F.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pezzuto, S.
    Russeil, D.
    Sauvage, M.
    Sibthorpe, B.
    Spinoglio, L.
    Testi, L.
    White, G.
    Wilson, C.
    Woodcraft, A.
    Zavagno, A.
    A Herschel study of the properties of starless cores in the Polaris Flare dark cloud region using PACS and SPIRE2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 518, p. L92-Article in journal (Refereed)
    Abstract [en]

    The Polaris Flare cloud region contains a great deal of extended emission. It is at high declination and high Galactic latitude. It was previously seen strongly in IRAS Cirrus emission at 100 microns. We have detected it with both PACS and SPIRE on Herschel. We see filamentary and low-level structure. We identify the five densest cores within this structure. We present the results of a temperature, mass and density analysis of these cores. We compare their observed masses to their virial masses, and see that in all cases the observed masses lie close to the lower end of the range of estimated virial masses. Therefore, we cannot say whether they are gravitationally bound prestellar cores. Nevertheless, these are the best candidates to be potential prestellar cores in the Polaris cloud region.

  • 86. Wesson, R.
    et al.
    Cernicharo, J.
    Barlow, M. J.
    Matsuura, M.
    Decin, L.
    Groenewegen, M. A. T.
    Polehampton, E. T.
    Agundez, M.
    Cohen, M.
    Daniel, F.
    Exter, K. M.
    Gear, W. K.
    Gomez, H. L.
    Hargrave, P. C.
    Imhof, P.
    Ivison, R. J.
    Leeks, S. J.
    Lim, T. L.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Savini, G.
    Sibthorpe, B.
    Swinyard, B. M.
    Ueta, T.
    Witherick, D. K.
    Yates, J. A.
    Herschel-SPIRE FTS spectroscopy of the carbon-rich objects AFGL 2688, AFGL 618, and NGC 70272010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 518, p. L144-Article in journal (Refereed)
    Abstract [en]

    We present far-infrared and submillimetre spectra of three carbon-rich evolved objects, AFGL 2688, AFGL 618 and NGC 7027. The spectra were obtained with the SPIRE Fourier-transform spectrometer on board the Herschel Space Observatory, and cover wavelengths from 195-670 mu m, a region of the electromagnetic spectrum hitherto difficult to study in detail. The far infrared spectra of these objects are rich and complex, and we measure over 150 lines in each object. Lines due to 18 different species are detected. We determine physical conditions from observations of the rotational lines of several molecules, and present initial large velocity gradient models for AFGL 618. We detect water in AFGL 2688 for the first time, and confirm its presence in AFGL 618 in both ortho and para forms. In addition, we report the detection of the J = 1-0 line of CH+ in NGC 7027.

  • 87. Wiegert, J.
    et al.
    Liseau, R.
    Thebault, P.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mora, A.
    Bryden, G.
    Marshall, J. P.
    Eiroa, C.
    Montesinos, B.
    Ardila, D.
    Augereau, J. C.
    Aran, A. Bayo
    Danchi, W. C.
    del Burgo, C.
    Ertel, S.
    Fridlund, M. C. W.
    Hajigholi, M.
    Krivov, A. V.
    Pilbratt, G. L.
    Roberge, A.
    White, G. J.
    Wolf, S.
    How dusty is alpha Centauri?: Excess or non-excess over the infrared photospheres of main-sequence stars2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 563, p. A102-Article in journal (Refereed)
    Abstract [en]

    Context. Debris discs around main-sequence stars indicate the presence of larger rocky bodies. The components of the nearby, solar-type binary alpha Centauri have metallicities that are higher than solar, which is thought to promote giant planet formation. Aims. We aim to determine the level of emission from debris around the stars in the alpha Cen system. This requires knowledge of their photospheres. Having already detected the temperature minimum, T-min, of alpha Cen A at far-infrared wavelengths, we here attempt to do the same for the more active companion alpha Cen B. Using the alpha Cen stars as templates, we study the possible effects that T-min may have on the detectability of unresolved dust discs around other stars. Methods. We used Herschel-PACS, Herschel-SPIRE, and APEX-LABOCA photometry to determine the stellar spectral energy distributions in the far infrared and submillimetre. In addition, we used APEX-SHeFI observations for spectral line mapping to study the complex background around alpha Cen seen in the photometric images. Models of stellar atmospheres and of particulate discs, based on particle simulations and in conjunction with radiative transfer calculations, were used to estimate the amount of debris around these stars. Results. For solar-type stars more distant than alpha Cen, a fractional dust luminosity f(d) equivalent to L-dust/L-star similar to 2 x 10(-7) could account for SEDs that do not exhibit the T-min effect. This is comparable to estimates of f(d) for the Edgeworth-Kuiper belt of the solar system. In contrast to the far infrared, slight excesses at the 2.5 sigma level are observed at 24 mu m for both alpha Cen A and B, which, if interpreted as due to zodiacal-type dust emission, would correspond to f(d) similar to (1-3) x 10(-5), i.e. some 10(2) times that of the local zodiacal cloud. Assuming simple power-law size distributions of the dust grains, dynamical disc modelling leads to rough mass estimates of the putative Zodi belts around the alpha Cen stars, viz. less than or similar to 4 x 10(-6) M-(sic) of 4 to 1000 mu m size grains, distributed according to n(a) proportional to a(-3.5). Similarly, for filled-in T-min emission, corresponding Edgeworth-Kuiper belts could account for similar to 10(-3) M-(sic) of dust. Conclusions. Our far-infrared observations lead to estimates of upper limits to the amount of circumstellar dust around the stars alpha Cen A and B. Light scattered and/or thermally emitted by exo-Zodi discs will have profound implications for future spectroscopic missions designed to search for biomarkers in the atmospheres of Earth-like planets. The far-infrared spectral energy distribution of alpha Cen B is marginally consistent with the presence of a minimum temperature region in the upper atmosphere of the star. We also show that an alpha Cen A-like temperature minimum may result in an erroneous apprehension about the presence of dust around other, more distant stars.

  • 88. Wilson, C. D.
    et al.
    Mason, A.
    Gregersen, E.
    Olofsson, A. O. H.
    Bergman, P.
    Booth, R.
    Boudet, N.
    Buat, V.
    Curry, C. L.
    Encrenaz, P.
    Falgarone, E.
    Feldman, P.
    Fich, M.
    Floren, H. G.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Frisk, U.
    Gerin, M.
    Harju, J.
    Hasegawa, T.
    Hjalmarson, Å.
    Juvela, M.
    Kwok, S.
    Larsson, B.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lecacheux, A.
    Liljestrom, T.
    Liseau, R.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mattila, K.
    Mitchell, G.
    Nordh, L.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Olberg, M.
    Olofsson, G.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Pagani, L.
    Plume, R.
    Ristorcelli, I.
    Sandqvist, Aa.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Serra, G.
    Tothill, N.
    Volk, K.
    von Scheele, F.
    Submillimeter emission from water in the W3 region2003In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, p. L59-L62Article in journal (Refereed)
    Abstract [en]

    Using the Odin satellite, we have mapped the submillimeter emission from the 110-101 transition of ortho-water in the W3 star-forming region. A 5arcminx 5arcmin map of the W3 IRS4 and W3 IRS5 region reveals strong water lines at half the positions in the map. The relative strength of the Odin lines compared to previous observations by SWAS suggests that we are seeing water emission from an extended region. Across much of the map the lines are double-peaked, with an absorption feature at -39 km s-1; however, some positions in the map show a single strong line at -43 km s-1. We interpret the double-peaked lines as arising from optically thick, self-absorbed water emission near the W3 IRS5, while the narrower blue-shifted lines originate in emission near W3 IRS4. In this model, the unusual appearance of the spectral lines across the map results from a coincidental agreement in velocity between the emission near W3 IRS4 and the blue peak of the more complex lines near W3 IRS5. The strength of the water lines near W3 IRS4 suggests we may be seeing water emission enhanced in a photon-dominated region. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation was the industrial prime contractor and is also responsible for the satellite operation.

  • 89. Wright, G
    et al.
    Andra, 13
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Andra, 6
    Design and development of MIRI, the mid-IR instrument for JWST2008In: Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter, 2008Conference paper (Other academic)
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