<i>HERSCHEL</i>OBSERVATIONS OF EXTRAORDINARY SOURCES: ANALYSIS OF THE HIFI 1.2 THz WIDE SPECTRAL SURVEY TOWARD ORION KL. I. METHODS

Crockett, N. R.; Bergin, Edwin A.; Neill, Justin L.; Favre, Cécile; Schilke, P.; Lis, D. C.; Bell, T. A.; Blake, Geoffrey A.; Cernicharo, J.; Emprechtinger, M.; Esplugues, G.; Gupta, H. M. Sen; Kleshcheva, M.; Lord, S. D.; Marcelino, N.; McGuire, Brett A.; Pearson, John C.; Phillips, T. G.; Plume, R.; Tak, F. F. S. van der; Tercero, B.; Yu, Shanshan

doi:10.1088/0004-637x/787/2/112

Cited by 117 publications

(172 citation statements)

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“…(1) Crockettt et al (2014b); (2) the start of the shock passage (at t = 0) and up to t ∼ 10 5 years, we predict that a higher maximum gas temperature reached leads to larger SO 2 abundances and lower SO abundances.…”

Section: Plateaumentioning

confidence: 82%

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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Section: Plateaumentioning

confidence: 82%

Modelling the sulphur chemistry evolution in Orion KL

Esplugues

Viti

Goicoechea

et al. 2014

A&A

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“…Among the studies aimed at identifying molecules in Orion, which is the reference source along with Sgr B2 in which to search for new species, many surveys have been conducted with single-dish telescopes from the ground (from some of the earliest works by Sutton et al 1985;Blake et al 1986, to recent observations with the IRAM-30 m, Tercero et al 2010Tercero et al , 2011Cernicharo et al 2016;etc. and with Herschel in a dedicated 1.2 THz bandwidth survey, Bergin et al 2010;Crockett et al 2014). With the sensitivity progress of the spectroradiometers, these surveys have reached the confusion limit; almost all the recorded channels contain emission of some species, implying strong blending and difficulty determining the baseline level.…”

Section: Introductionmentioning

confidence: 99%

The complexity of Orion: an ALMA view

Pagani

Favre

Goldsmith

et al. 2017

A&A

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Context. We wish to improve our understanding of the Orion central star formation region (Orion-KL) and disentangle its complexity. Aims. We collected data with ALMA during cycle 2 in 16 GHz of total bandwidth spread between 215.1 and 252.0 GHz with a typical sensitivity of 5 mJy/beam (2.3 mJy/beam from 233.4 to 234.4 GHz) and a typical beam size of 1 . 7 × 1 . 0 (average position angle of 89 • ). We produced a continuum map and studied the emission lines in nine remarkable infrared spots in the region including the hot core and the compact ridge, plus the recently discovered ethylene glycol peak. Methods. We present the data, and report the detection of several species not previously seen in Orion, including n-and i-propyl cyanide (C 3 H 7 CN), and the tentative detection of a number of other species including glycolaldehyde (CH 2 (OH)CHO). The first detections of gGg ethylene glycol (gGg (CH 2 OH) 2 ) and of acetic acid (CH 3 COOH) in Orion are presented in a companion paper. We also report the possible detection of several vibrationally excited states of cyanoacetylene (HC 3 N), and of its 13 C isotopologues. We were not able to detect the 16 O 18 O line predicted by our detection of O 2 with Herschel, due to blending with a nearby line of vibrationally excited ethyl cyanide. We do not confirm the tentative detection of hexatriynyl (C 6 H) and cyanohexatriyne (HC 7 N) reported previously, or of hydrogen peroxide (H 2 O 2 ) emission. Results. We report a complex velocity structure only partially revealed before. Components as extreme as −7 and +19 km s −1 are detected inside the hot region. Thanks to different opacities of various velocity components, in some cases we can position these components along the line of sight. We propose that the systematically redshifted and blueshifted wings of several species observed in the northern part of the region are linked to the explosion that occurred ∼500 yr ago. The compact ridge, noticeably farther south displays extremely narrow lines (∼1 km s −1 ) revealing a quiescent region that has not been affected by this explosion. This probably indicates that the compact ridge is either over 10 000 au in front of or behind the rest of the region. Conclusions. Many lines remain unidentified, and only a detailed modeling of all known species, including vibrational states of isotopologues combined with the detailed spatial analysis offered by ALMA enriched with zero-spacing data, will allow new species to be detected.

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“…This makes the Becklin-Neugebauer and Kleinmann-Low Nebula in Orion (Orion BN/KL), at a distance of 414 ± 7 pc (Sandstrom et al 2007;Menten et al 2007), ideal for studies of the physical and chemical properties of HMSFRs. As the nearest HMSFR, it has been extensively studied at both far-infrared to (sub) millimetre wavelengths accessible from space (e.g., Olofsson et al 2007;Bergin et al 2010;Crockett et al 2014) and at radio, millimetre, and submillimetre wavelengths accessible from the ground. A broad range of studies on this source have been conducted either with single-dish telescopes (e.g., Johansson et al 1984;Sutton et al 1985;Blake et al 1987;Turner 1989;Greaves & White 1991;Schilke et al 1997Schilke et al , 2001; Lee & Cho 2002;Comito et al 2005;Remijan et al 2008;Tercero et al 2010) or interferometers (e.g., Wright et al 1996;Blake et al 1996;Beuther et al 2005Beuther et al , 2006Friedel & Snyder 2008;Guélin et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Resolving the chemical substructure of Orion-KL

Feng

Beuther

Henning

et al. 2015

A&A

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Context. The Kleinmann-Low nebula in Orion (Orion-KL) is the nearest example of a high-mass star-forming environment. Studying the resolved chemical substructures of this complex region provides important insight into the chemistry of high-mass star-forming regions (HMSFRs), as it relates to their evolutionary states. Aims. The goal of this work is to resolve the molecular line emission from individual substructures of Orion-KL at high spectral and spatial resolution and to infer the chemical properties of the associated gas.Methods. We present a line survey of Orion-KL obtained from combined Submillimeter Array (SMA) interferometric and IRAM 30 m single-dish observations. Covering a 4 GHz bandwidth in total, this survey contains over 160 emission lines from 20 species (25 isotopologues), including 11 complex organic molecules (COMs). Spectra are extracted from individual substructures and the intensity-integrated distribution map for each species is provided. We then estimate the rotation temperature for each substructure, along with their molecular column densities and abundances. Results. For the first time, we complement 1.3 mm interferometric data with single-dish observations of the Orion-KL region and study small-scale chemical variations in this region. (1) We resolve continuum substructures on ∼3 angular scale. (2) We identify lines from the low-abundance COMs CH 3 COCH 3 and CH 3 CH 2 OH, as well as tentatively detect CH 3 CHO and long carbon-chain molecules C 6 H and HC 7 N. (3) We find that while most COMs are segregated by type, peaking either towards the hotcore (e.g., nitrogenbearing species) or the compact ridge (e.g., oxygen-bearing species like HCOOCH 3 and CH 3 OCH 3 ), the distributions of others do not follow this segregated structure (e.g., CH 3 CH 2 OH, CH 3 OH, CH 3 COCH 3 ). (4) We find a second velocity component of HNCO, SO 2 , 34 SO 2 , and SO lines, which may be associated with a strong shock event in the low-velocity outflow. (5) Temperatures and molecular abundances show large gradients between central condensations and the outflow regions, illustrating a transition between hot molecular core and shock-chemistry dominated regimes. Conclusions. Our observations of spatially resolved abundance variations in Orion-KL provide the nearest reference source for hot molecular core and outflow chemistry, which will be an important example for interpreting the chemistry of more distant HMSFRs.

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HERSCHELOBSERVATIONS OF EXTRAORDINARY SOURCES: ANALYSIS OF THE HIFI 1.2 THz WIDE SPECTRAL SURVEY TOWARD ORION KL. I. METHODS

Cited by 117 publications

References 110 publications

Modelling the sulphur chemistry evolution in Orion KL

Modelling the sulphur chemistry evolution in Orion KL

The complexity of Orion: an ALMA view

Resolving the chemical substructure of Orion-KL

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