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5 results on '"ISM: individual objects (Orion)"'

1. Large-scale CO (J=4-3) mapping toward the Orion-A giant molecular cloud.

Author

Shun ISHII, Masumichi SETA, Makoto NAGAI, Yusuke MIYAMOTO, Naomasa NAKAI, Taketo NAGASAKI, Hitoshi ARAI, Hiroaki IMADA, Naoki MIYAGAWA, Hiroyuki MAEZAWA, Hideki MAEHASHI, Leonardo BRONFMAN, and Ricardo FINGER

Subjects
*MOLECULAR clouds, *ORION Nebula, *LOCAL thermodynamic equilibrium, *CARBON monoxide, *RADIATIVE transfer, *INTERSTELLAR gases
Abstract

We have mapped the Orion-A giant molecular cloud in the CO(J=4-3) line with the Tsukuba 30cm submillimeter telescope. The map covered a 7.125 deg2 area with a 9' resolution, including main components of the cloud such as the Orion Nebula, OMC- 2/3, and L1641-N. The most intense emission was detected toward the Orion KL region. The integrated intensity ratio between CO(J=4-3) and CO(J=1-0) was derived using data from the Columbia-Universidad de Chile CO survey, which was carried out with a comparable angular resolution. The ratio was r4−3/1−0 ∼0.2 in the southern region of the cloud and 0.4-0.8 at star forming regions. We found a trend that the ratio shows higher values at the edges of the cloud. In particular, the ratio at the northeastern edge of the cloud at (l, b) ≈ (208. ° 375, −19. ° 0) shows the highest value of 1.1. The physical condition of the molecular gas in the cloud was estimated by non-LTE calculation. The result indicates that the kinetic temperature has a gradient from north (Tkin = 80 K) to south (20 K). The estimation shows that the gas associated with the edge of the cloud is warm (Tkin ∼60 K), dense (nH2 ∼ 104 cm−3), and optically thin, which may be explained by heating and sweeping of interstellar materials from OB clusters. [ABSTRACT FROM AUTHOR]

Published
2016
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2. KECK ADAPTIVE OPTICS OBSERVATIONS OF THE PROTOSTELLAR DISK AROUND RADIO SOURCE I IN THE ORION KLEINMANN-LOW NEBULA.

Author

SITARSKI, BREANN N., MORRIS, MARK R., LU, JESSICA R., DUCHÊNE, GASPARD, STOLTE, ANDREA, BECKLIN, E. E., GHEZ, ANDREA M., and ZINNECKER, HANS

Subjects
*ADAPTIVE optics, *STELLAR activity, *ORION (Constellation), *NEBULA spectra, *INFRARED radiation
Abstract

We have made the first detection of a near-infrared counterpart associated with the disk around Radio Source "I," a massive protostar in the Kleinmann-Low nebula in Orion, using imaging with laser guide star adaptive optics on the Keck II telescope. The infrared emission is evident in images acquired using L' (3.8 μm) and Ms (4.7 μm) filters and is not detectable at K' (2.1 μm). The observed morphology strongly suggests that we are seeing some combination of scattered and thermal light emanating from the disk. The disk is also manifest in the L' /Ms flux ratio image. We interpret the near-infrared emission as the illuminated surface of a nearly edge-on disk, oriented so that only the northern face is visible; the opposite surface remains hidden by the disk. We do not see infrared radiation associated directly with the star proposed to be associated with Source "I." The data also suggest that there is a cavity above and below the disk that is oriented perpendicular to the disk and is sculpted by the known, strong outflow from the inner disk of Source I. We compare our data to models of a protostar with a surrounding disk, envelope, and wind-blown cavity in order to elucidate the nature of the disk around Radio Source I. [ABSTRACT FROM AUTHOR]

Published
2013
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3. HERSCHEL MEASUREMENTS OF MOLECULAR OXYGEN IN ORION.

Author

GOLDSMITH, PAUL F., LISEAU, RENÉ, BELL, TOM A., BLACK, JOHN H., CHEN, JO-HSIN, Hollenbach, David, KAUFMAN, MICHAEL J., LI, DI, LIS, DARIUSZ C., MELNICK, GARY, NEUFELD, DAVID, PAGANI, LAURENT, SNELL, RONALD, BENZ, ARNOLD O., BERGIN, EDWIN, BRUDERER, SIMON, CASELLI, PAOLA, CAUX, EMMANUEL, ENCRENAZ, PIERRE, and FALGARONE, EDITH

Subjects
*ORION (Constellation), *CONSTELLATIONS, *OXYGEN, *HYDROGEN, *MOLECULES
Abstract

We report observations of three rotational transitions of molecular oxygen (O2) in emission from the H2 Peak 1 position of vibrationally excited molecular hydrogen in Orion. We observed the 487 GHz, 774 GHz, and 1121 GHz lines using the Heterodyne Instrument for the Far Infrared on the Herschel Space Observatory, having velocities of 11 km s–1 to 12 km s–1 and widths of 3 km s–1. The beam-averaged column density is N(O2) = 6.5 × 1016 cm–2, and assuming that the source has an equal beam-filling factor for all transitions (beam widths 44, 28, and 19''), the relative line intensities imply a kinetic temperature between 65 K and 120 K. The fractional abundance of O2 relative to H2 is (0.3-7.3) × 10–6. The unusual velocity suggests an association with a ~5'' diameter source, denoted Peak A, the Western Clump, or MF4. The mass of this source is ~10 M ☉ and the dust temperature is ≥150 K. Our preferred explanation of the enhanced O2 abundance is that dust grains in this region are sufficiently warm (T ≥ 100 K) to desorb water ice and thus keep a significant fraction of elemental oxygen in the gas phase, with a significant fraction as O2. For this small source, the line ratios require a temperature ≥180 K. The inferred O2 column density 5 × 1018 cm–2 can be produced in Peak A, having N(H2) 4 × 1024 cm–2. An alternative mechanism is a low-velocity (10-15 km s–1) C-shock, which can produce N(O2) up to 1017 cm–2. [ABSTRACT FROM AUTHOR]

Published
2011
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4. Herschel Search for O2 toward the Orion Bar

Author

David J. Hollenbach, Pierre Encrenaz, Edith Falgarone, Ewine F. van Dishoeck, Gary J. Melnick, René Liseau, Åke Hjalmarson, David A. Neufeld, Maryvonne Gerin, John H. Black, Paul F. Goldsmith, Volker Tolls, Michael J. Kaufman, Di Li, Floris van der Tak, Laurent Pagani, Ronald L. Snell, Dariusz C. Lis, Astronomy, Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Center for Cognitive Ubiquitous Computing, Arizona State University [Tempe] (ASU), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Centre Procédés, Énergies Renouvelables, Systèmes Énergétiques (PERSEE), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Department of Radio and Space Science [Göteborg], Chalmers University of Technology [Göteborg], Department of Physics and Astronomy [Baltimore], Johns Hopkins University (JHU), SRON Netherlands Institute for Space Research (SRON), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], NASA-California Institute of Technology (CALTECH), École normale supérieure - Paris (ENS-PSL), Mines Paris - PSL (École nationale supérieure des mines de Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and Universiteit Leiden

Subjects
Flux, FOS: Physical sciences, Astrophysics, Photodissociation region, 010402 general chemistry, 01 natural sciences, ISM: abundances, REGION, ISM: individual objects (Orion), Far infrared, 0103 physical sciences, 010303 astronomy & astrophysics, INTERSTELLAR CHLORONIUM, MILLIMETER, ComputingMilieux_MISCELLANEOUS, Line (formation), Physics, [PHYS]Physics [physics], CHEMICAL-MODELS, Line-of-sight, Filling factor, astrochemistry, WATER ICE, Astronomy and Astrophysics, THERMAL BALANCE, Astrophysics - Astrophysics of Galaxies, ISM: molecules, 0104 chemical sciences, Stars, SUBMILLIMETER OBSERVATIONS, 13. Climate action, Space and Planetary Science, PHOTODESORPTION, Astrophysics of Galaxies (astro-ph.GA), MOLECULAR CLOUDS, submillimeter: ISM, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], EMISSION, Bar (unit)
Abstract

We report the results of a search for molecular oxygen (O2) toward the Orion Bar, a prominent photodissociation region at the southern edge of the HII region created by the luminous Trapezium stars. We observed the spectral region around the frequency of the O2 N_J = 3_3 - 1_2 transition at 487 GHz and the 5_4 - 3_4 transition at 774 GHz using the Heterodyne Instrument for the Far Infrared on the Herschel Space Observatory. Neither line was detected, but the 3sigma upper limits established here translate to a total line-of-sight O2 column density < 1.5 10^16 cm^-2 for an emitting region whose temperature is between 30K and 250 K, or < 1 10^16 cm^-2 if the O2 emitting region is primarily at a temperature of ~< 100 K. Because the Orion Bar is oriented nearly edge-on relative to our line of sight, the observed column density is enhanced by a factor estimated to be between 4 and 20 relative to the face-on value. Our upper limits imply that the face-on O2 column density is less than 4 10^15 cm^-2, a value that is below, and possibly well below, model predictions for gas with a density of 10^4 - 10^5 cm^-3 exposed to a far ultraviolet flux 10^4 times the local value, conditions inferred from previous observations of the Orion Bar. The discrepancy might be resolved if: (1) the adsorption energy of O atoms to ice is greater than 800 K; (2) the total face-on Av of the Bar is less than required for O2 to reach peak abundance; (3) the O2 emission arises within dense clumps with a small beam filling factor; or, (4) the face-on depth into the Bar where O2 reaches its peak abundance, which is density dependent, corresponds to a sky position different from that sampled by our Herschel beams., 30 pages, 7 figures, 1 table. Accepted for publication in ApJ

Published
2012

5. Herschel Measurements of Molecular Oxygen in Orion

Author

Paul F. Goldsmith, René Liseau, Tom A. Bell, John H. Black, Jo-Hsin Chen, David Hollenbach, Michael J. Kaufman, Di Li, Dariusz C. Lis, Gary Melnick, David Neufeld, Laurent Pagani, Ronald Snell, Arnold O. Benz, Edwin Bergin, Simon Bruderer, Paola Caselli, Emmanuel Caux, Pierre Encrenaz, Edith Falgarone, Maryvonne Gerin, Javier R. Goicoechea, Åke Hjalmarson, Bengt Larsson, Jacques Le Bourlot, Franck Le Petit, Massimo De Luca, Zsofia Nagy, Evelyne Roueff, Aage Sandqvist, Floris van der Tak, Ewine F. van Dishoeck, Charlotte Vastel, Serena Viti, Umut Yıldız, Astronomy, Department of Radio and Space Science [Göteborg], Chalmers University of Technology [Göteborg], Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Onsala Space Observatory (OSO), SRON Netherlands Institute for Space Research (SRON), Max-Planck-Institut für Radioastronomie (MPIFR), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Harvard University-Smithsonian Institution, Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), Smithsonian Institution-Harvard University [Cambridge], Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
ROTATIONAL-EXCITATION, WAVE-ASTRONOMY-SATELLITE, DISSOCIATIVE RECOMBINATION, Mean kinetic temperature, Abundance (chemistry), FOS: Physical sciences, Astrophysics, 7. Clean energy, 01 natural sciences, ISM: abundances, ISM: individual objects (Orion), O-2 ABUNDANCE, UPPER LIMITS, 0103 physical sciences, 010303 astronomy & astrophysics, Line (formation), ISM: individual objects: Orion, Physics, DENSE INTERSTELLAR CLOUDS, GAS-PHASE CHEMISTRY, 010308 nuclear & particles physics, Filling factor, astrochemistry, Astronomy and Astrophysics, Elemental oxygen, INTER-STELLAR CLOUDS, APERTURE SYNTHESIS, Astrophysics - Astrophysics of Galaxies, ISM: molecules, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Excited state, submillimeter: ISM, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Molecular oxygen, INELASTIC-COLLISIONS, Beam (structure)
Abstract

International audience; We report observations of three rotational transitions of molecular oxygen (O2) in emission from the H2 Peak 1 position of vibrationally excited molecular hydrogen in Orion. We observed the 487 GHz, 774 GHz, and 1121 GHz lines using the Heterodyne Instrument for the Far Infrared on the Herschel Space Observatory, having velocities of 11 km s-1 to 12 km s-1 and widths of 3 km s-1. The beam-averaged column density is N(O2) = 6.5 × 1016 cm-2, and assuming that the source has an equal beam-filling factor for all transitions (beam widths 44, 28, and 19''), the relative line intensities imply a kinetic temperature between 65 K and 120 K. The fractional abundance of O2 relative to H2 is (0.3-7.3) × 10-6. The unusual velocity suggests an association with a ~5'' diameter source, denoted Peak A, the Western Clump, or MF4. The mass of this source is ~10 M sun and the dust temperature is >=150 K. Our preferred explanation of the enhanced O2 abundance is that dust grains in this region are sufficiently warm (T >= 100 K) to desorb water ice and thus keep a significant fraction of elemental oxygen in the gas phase, with a significant fraction as O2. For this small source, the line ratios require a temperature >=180 K. The inferred O2 column density sime5 × 1018 cm-2 can be produced in Peak A, having N(H2) ~= 4 × 1024 cm-2. An alternative mechanism is a low-velocity (10-15 km s-1) C-shock, which can produce N(O2) up to 1017 cm-2. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Published
2011

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