Deuterated methanol in Orion BN/KL

Peng, T.-C.; Despois, D.; Brouillet, N.; Parise, B.; Baudry, A.

doi:10.1051/0004-6361/201118310

Cited by 54 publications

(79 citation statements)

References 58 publications

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“…From this check, we derived low opacities (values below 1) in all sources, so that we decided to compute N and T rot assuming optically thin conditions too. As for NH 3 and NH 2 D, the source sizes of CH 3 OH and CH 2 DOH are unknown, but they are expected to be smaller than the beam size and to have a comparable extent, based on observations at high angular resolution in Orion (Peng et al 2012). Therefore, to take the beam dilution into account, the column densities in the rotation diagrams were corrected by assuming the same source sizes as in Paper I, namely 6.5, 4.1, and 5.5 for HMSCs, HMPOs, and UC Hiis, assuming that methanol and its deuterated forms trace approximately the same material.…”

Section: Derivation Of Molecular Column Densities and Rotation Tempermentioning

confidence: 99%

Deuteration and evolution in the massive star formation process

Fontani

Busquet

Palau

et al. 2015

A&A

131

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Context. An ever growing number of observational and theoretical evidence suggests that the deuterated fraction (column density ratio between a species containing D and its hydrogenated counterpart, D frac ) is an evolutionary indicator both in the low-and the highmass star formation process. However, the role of surface chemistry in these studies has not been quantified from an observational point of view. Aims. Because many abundant species, such as NH 3 , H 2 CO, and CH 3 OH, are actively produced on ice mantles of dust grains during the early cold phases, their D frac is expected to evolve differently from species formed only (or predominantly) in the gas, such as N 2 H + , HNC, HCN, and their deuterated isotopologues. The differences are expected to be relevant especially after the protostellar birth, in which the temperature rises, causing the evaporation of ice mantles. Methods. To compare how the deuterated fractions of species formed only in the gas and partially or uniquely on grain surfaces evolve with time, we observed rotational transitions of CH 3 OH, 13 CH 3 OH, CH 2 DOH, and CH 3 OD at 3 mm and 1.3 mm, of NH 2 D at 3 mm with the IRAM-30 m telescope, and the inversion transitions (1, 1) and (2, 2) of NH 3 with the GBT, towards most of the cores already observed in N 2 H + , N 2 D + , HNC, and DNC. Results. NH 2 D is detected in all but two cores, regardless of the evolutionary stage. D frac (NH 3 ) is on average above 0.1 and does not change significantly from the earliest to the most evolved phases, although the highest average value is found in the protostellar phase (∼0.3). Few lines of CH 2 DOH and CH 3 OD are clearly detected, and then only towards protostellar cores or externally heated starless cores. In quiescent starless cores, we have only one doubtful detection of CH 2 DOH. Conclusions. This work clearly confirms an expected different evolutionary trend of the species formed exclusively in the gas (N 2 D + and N 2 H + ) and those formed partially (NH 2 D and NH 3 ) or totally (CH 2 DOH and CH 3 OH) on grain mantles. It also reinforces the idea that D frac (N 2 H + ) is the best tracer of massive starless cores, while high values of D frac (CH 3 OH) seem fairly good tracers of the early protostellar phases, where the evaporation or sputtering of the grain mantles is most efficient.

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Section: Derivation Of Molecular Column Densities and Rotation Tempermentioning

confidence: 99%

Deuteration and evolution in the massive star formation process

Fontani

Busquet

Palau

et al. 2015

A&A

131

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“…Naturally, interferometers have been used to separate the components, diminish the confusion, and help understand the ongoing evolution of the chemical and physical complex structure (e.g. Favre et al 2011a;Peng et al 2012Peng et al , 2017Brouillet et al 2013;Feng et al 2015;Tercero et al 2015).…”

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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“…From a set of twelve Plateau de Bure observations, we have recently analyzed the deuterated methanol isotopologues A&A 550, A46 (2013) CH 2 DOH and CH 3 OD (Peng et al 2012) and the methyl formate HCOOCH 3 (Favre et al 2011a) emission in Orion KL. The latter work suggests a rather close morphological relation in several places of the Orion KL nebula between excited H 2 emission at 2.12 μm and methyl formate.…”

Section: Introductionmentioning

confidence: 99%

CH₃OCH₃in Orion-KL: a striking similarity with HCOOCH₃

Brouillet

Despois

Baudry

et al. 2013

A&A

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Context. Orion-KL is a remarkable, nearby star-forming region where a recent explosive event has generated shocks that could have released complex molecules from the grain mantles. Aims. A comparison of the distribution of the different complex molecules will help in understanding their formation and constraining the chemical models.Methods. We used several data sets from the Plateau de Bure Interferometer to map the dimethyl ether emission with different arcsec spatial resolutions and different energy levels (from E up = 18 to 330 K) to compare with our previous methyl formate maps. Results. Our data show remarkable similarity between the dimethyl ether (CH 3 OCH 3 ) and the methyl formate (HCOOCH 3 ) distributions even on a small scale (1.8 × 0.8 or ∼500 AU). This long suspected similarity, seen from both observational and theoretical arguments, is demonstrated with unprecedented confidence, with a correlation coefficient of maps ∼0.8. Conclusions. A common precursor is the simplest explanation of our correlation. Comparisons with previous laboratory work and chemical models suggest the major role of grain surface chemistry and a recent release, probably with little processing, of mantle molecules by shocks. In this case the CH 3 O radical produced from methanol ice would be the common precursor (whereas ethanol, C 2 H 5 OH, is produced from the radical CH 2 OH). The alternative gas phase scheme, where protonated methanol CH 3 OH + 2 is the common precursor to produce methyl formate and dimethyl ether through reactions with HCOOH and CH 3 OH, is also compatible with our data. Our observations cannot yet definitely allow a choice between the different chemical processes, but the tight correlation between the distributions of HCOOCH 3 and CH 3 OCH 3 strongly contrasts with the different behavior we observe for the distributions of ethanol and formic acid. This provides a very significant constraint on models.

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Deuterated methanol in Orion BN/KL

Cited by 54 publications

References 58 publications

Deuteration and evolution in the massive star formation process

Deuteration and evolution in the massive star formation process

The complexity of Orion: an ALMA view

CH₃OCH₃in Orion-KL: a striking similarity with HCOOCH₃

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Deuterated methanol in Orion BN/KL

Cited by 54 publications

References 58 publications

Deuteration and evolution in the massive star formation process

Deuteration and evolution in the massive star formation process

The complexity of Orion: an ALMA view

CH3OCH3in Orion-KL: a striking similarity with HCOOCH3

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CH₃OCH₃in Orion-KL: a striking similarity with HCOOCH₃