<i>HERSCHEL</i>MEASUREMENTS OF MOLECULAR OXYGEN IN ORION

Goldsmith, Paul F.; Liseau, R.; Bell, T. A.; Black, J. H.; Chen, Jo Hsin; Hollenbach, D. J.; Kaufman, Michael J.; Li, Di; Lis, D.; Melnick, Gary J.; Neufeld, David A.; Pagani, L.; Snell, R. L.; Benz, A. O.; Bergin, Edwin A.; Bruderer, S.; Caselli, P.; Caux, E.; Encrenaz, P.; Falgarone, É.; Gérin, M.; Goicoechea, J. R.; Hjalmarson, Å.; Larsson, Bengt; Bourlot, J. Le; Petit, Franck; Luca, Massimo De; Nagy, Z.; Roueff, E.; Sandqvist, Aage; Tak, F. F. S. van der; Dishoeck, E. F. van; Vastel, C.; Viti, S.; Yıldız, U. A.

doi:10.1088/0004-637x/737/2/96

Cited by 148 publications

(162 citation statements)

References 98 publications

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“…For instance, the limit on the O 2 column in Ori A determined by Pagani et al (2003) is entirely consistent with the HIFI beamaveraged detection obtained by Goldsmith et al (2011), if proper correction for dilution in the Odin-beam is applied. We recall that the detected spot is not toward the Orion-PDR (Melnick et al 2012), as one might have expected, but close to the outflow in the vicinity of IRc 2.…”

Section: Source(s) Of O 2 or The Dearth Of Osupporting

confidence: 81%

“…It is therefore surprising that O 2 has been detected only toward the dense cloud core ρ Oph A (Larsson et al 2007, and this work) and a spot in OMC-1 (Goldsmith et al 2011), despite numerous searches toward other regions. For instance, surveying twenty sources, Goldsmith et al (2000) obtained limiting O 2 abundances N(O 2 )/N(H 2 ) of a few times 10 −7 , whereas Pagani et al (2003) derived upper limits to the O 2 column density of 10 15 to a few times 10 16 cm −2 for nearly a dozen objects.…”

Section: Source(s) Of O 2 or The Dearth Of Omentioning

confidence: 59%

“…Consequently, large efforts, from both the ground (O 18 O) and space, were made to obtain quantitative estimates of its abundance. The historical account of this essentially fruitless "O 2 -struggle" was reviewed by Goldsmith et al (2011). Prior to Herschel, both SWAS Goldsmith et al 2000) and Odin (Nordh et al 2003;Pagani et al 2003) had already shown that the abundances of both O 2 and H 2 O assumed by Goldsmith & Langer (1978) were much higher than actual values in the ISM and, with the exception of the ρ Oph cloud, none of the O 2 lines were detected anywhere Based on observations with Herschel-HIFI.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, ρ Oph A displays an interesting chemistry: doubly deuterated formaldehyde (D 2 CO) and hydrogen peroxide (H 2 O 2 ) molecules, rarely seen elsewhere in the ISM, A&A 541, A73 (2012) Roelfsema et al (2012) Notes. (a) An energy level diagram is provided by, e.g., Goldsmith et al (2011). (b) Frequencies are from the JPL-catalogue http://spec.jpl.nasa.gov/cgi-bin/catform Grasdalen et al (1973), Elias (1978) have for example been found here (Bergman et al 2011a,b).…”

Section: Introductionmentioning

confidence: 99%

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Multi-line detection of O₂towardρOphiuchi A

Liseau

Goldsmith

Larsson

et al. 2012

A&A

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Context. Models of pure gas-phase chemistry in well-shielded regions of molecular clouds predict relatively high levels of molecular oxygen, O 2 , and water, H 2 O. These high abundances imply high cooling rates, leading to relatively short timescales for the evolution of gravitationally unstable dense cores, forming stars and planets. Contrary to expectations, the dedicated space missions SWAS and Odin typically found only very small amounts of water vapour and essentially no O 2 in the dense star-forming interstellar medium. Aims. Only toward ρ Oph A did Odin detect a very weak line of O 2 at 119 GHz in a beam of size 10 arcmin. The line emission of related molecules changes on angular scales of the order of some tens of arcseconds, requiring a larger telescope aperture such as that of the Herschel Space Observatory to resolve the O 2 emission and pinpoint its origin. Methods. We use the Heterodyne Instrument for the Far Infrared (HIFI) aboard Herschel to obtain high resolution O 2 spectra toward selected positions in the ρ Oph A core. These data are analysed using standard techniques for O 2 excitation and compared to recent PDR-like chemical cloud models.Results. The N J = 3 3 −1 2 line at 487.2 GHz is clearly detected toward all three observed positions in the ρ Oph A core. In addition, an oversampled map of the 5 4 −3 4 transition at 773.8 GHz reveals the detection of the line in only half of the observed area. On the basis of their ratios, the temperature of the O 2 emitting gas appears to vary quite substantially, with warm gas ( > ∼ 50 K) being adjacent to a much colder region, of temperatures lower than 30 K. Conclusions. The exploited models predict that the O 2 column densities are sensitive to the prevailing dust temperatures, but rather insensitive to the temperatures of the gas. In agreement with these models, the observationally determined O 2 column densities do not seem to depend strongly on the derived gas temperatures, but fall into the range N(O 2 ) = 3 to > ∼ 6 × 10 15 cm −2 . Beam-averaged O 2 abundances are about 5 × 10 −8 relative to H 2 . Combining the HIFI data with earlier Odin observations yields a source size at 119 GHz in the range of 4 to 5 arcmin, encompassing the entire ρ Oph A core. We speculate that one of the reasons for the generally very low detection rate of O 2 is the short period of time during which O 2 molecules are reasonably abundant in molecular clouds.

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Section: Source(s) Of O 2 or The Dearth Of Osupporting

confidence: 81%

Section: Source(s) Of O 2 or The Dearth Of Omentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multi-line detection of O₂towardρOphiuchi A

Liseau

Goldsmith

Larsson

et al. 2012

A&A

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“…Goicoechea et al (2006b) found a fractional abundance of X(OH) = (0.5−1) × 10 −6 in the plateau and Goldsmith et al (2011) obtained X(O 2 ) = (0.3−7) × 10 −6 , deducing that this value is the result of an enhancement of X(O 2 ) by shocks. In fact, we have represented the evolution of the OH/O 2 ratio, Fig.…”

Section: Sulphur Chemical Evolution In the Plateaumentioning

confidence: 97%

Modelling the sulphur chemistry evolution in Orion KL

Esplugues

Viti

Goicoechea

et al. 2014

A&A

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Context. We present a study of the sulphur chemistry evolution in the region Orion KL along the gas and grain phases of the cloud. Aims. Our aim is to investigate the processes that dominate the sulphur chemistry in Orion KL and to determine how physical and chemical parameters, such as the final mass of the star and the initial elemental abundances, influence the evolution of the hot core and of the surrounding outflows and shocked gas (the plateau). Methods. We independently modelled the chemistry evolution of the hot core and the plateau using the time-dependent gas-grain model UCL_CHEM and considering two different phase calculations. Phase I starts with the collapsing cloud and the depletion of atoms and molecules onto grain surfaces. Phase II starts when a central protostar is formed and the evaporation from grains takes place. We show how the stellar mass, the gas density, the gas depletion efficiency, the initial sulphur abundance, the shocked gas temperature, and the different chemical paths on the grains leading to different reservoirs of sulphur on the mantles affect sulphurbearing molecules at different evolutionary stages for both components. We also compare the predicted column densities with those inferred from observations of the species SO, SO 2 , CS, OCS, H 2 S, and H 2 CS.Results. The models that reproduce the observations of the largest number of sulphur-bearing species in both components are those with an initial sulphur abundance of 0.1 times the sulphur solar abundance (0.1 S ) and a density of at least n H = 5 × 10 6 cm −3 in the shocked gas region. Conclusions. We conclude that most of the sulphur atoms were ionised during Phase I, consistent with an inhomogeneous and clumpy region where the UV interstellar radiation penetrates and leading to sulphur ionisation. We also conclude that the main sulphur reservoir on the ice mantles was H 2 S. In addition, we deduce that a chemical transition currently takes place in the plateau shocked gas, where SO and SO 2 gas-phase formation reactions change from being dominated by O 2 to being dominated by OH.

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Antagonistic Functionalized Nucleation and Oxidative Degradation in Combustive Formation of Pyrene‐Based Clusters Mediated by Triplet O and O₂: Theoretical Study

Maranzana

Tonachini

2015

ChemPhysChem

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Abstract.Polycyclic aromatic hydrocarbons (PAHs) and carbonaceous nanoparticles can be oxidized right from their inception and all through their growth. Oxidation can promote their degradation too. This modelistic density functional theory (DFT) study explores in a descriptive manner if oxidation can mediate the earliest nucleation stages ("functionalized nucleation"), though contrasted by mass declension triggered by oxidation itself. An initial O (

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HERSCHELMEASUREMENTS OF MOLECULAR OXYGEN IN ORION

Abstract: We report observations of three rotational transitions of molecular oxygen (O 2 ) in emission from the H 2 Peak

Cited by 148 publications

References 98 publications

Multi-line detection of O₂towardρOphiuchi A

Multi-line detection of O₂towardρOphiuchi A

Modelling the sulphur chemistry evolution in Orion KL

Antagonistic Functionalized Nucleation and Oxidative Degradation in Combustive Formation of Pyrene‐Based Clusters Mediated by Triplet O and O₂: Theoretical Study

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HERSCHELMEASUREMENTS OF MOLECULAR OXYGEN IN ORION

Abstract: We report observations of three rotational transitions of molecular oxygen (O 2 ) in emission from the H 2 Peak

Cited by 148 publications

References 98 publications

Multi-line detection of O2towardρOphiuchi A

Multi-line detection of O2towardρOphiuchi A

Modelling the sulphur chemistry evolution in Orion KL

Antagonistic Functionalized Nucleation and Oxidative Degradation in Combustive Formation of Pyrene‐Based Clusters Mediated by Triplet O and O2: Theoretical Study

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Product

Resources

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Multi-line detection of O₂towardρOphiuchi A

Multi-line detection of O₂towardρOphiuchi A

Antagonistic Functionalized Nucleation and Oxidative Degradation in Combustive Formation of Pyrene‐Based Clusters Mediated by Triplet O and O₂: Theoretical Study