Universität zu Köln

Coletta, A., Fontani, F., Rivilla, V. M., Mininni, C., Colzi, L., Sanchez-Monge, A. and Beltran, M. T. (2020). Evolutionary study of complex organic molecules in high-mass star-forming regions. Astron. Astrophys., 641. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

We have studied four complex organic molecules (COMs), the oxygen-bearing methyl formate (CH3OCHO) and dimethyl ether (CH3OCH3) as well as the nitrogen-bearing formamide (NH2CHO) and ethyl cyanide (C2H5CN), towards a large sample of 39 high-mass star-forming regions representing different evolutionary stages, from early to evolved phases. We aim to identify potential correlations and chemical links between the molecules and to trace their evolutionary sequence through the star formation process. We analysed spectra obtained at 3, 2, and 0.9 mm with the IRAM-30m telescope. We derived the main physical parameters for each species by fitting the molecular lines. We compared them and evaluated their evolution while also taking several other interstellar environments into account. We report detections in 20 sources, revealing a clear dust absorption effect on column densities. Derived abundances range between similar to 10(-10)-10(-7) for CH3OCHO and CH3OCH3, similar to 10(-12)-10(-10) for NH2CHO, and similar to 10(-11)-10(-9) for C2H5CN. The abundances of CH3OCHO, CH3OCH3, and C2H5CN are very strongly correlated (r >= 0.92) across similar to 4 orders of magnitude. We note that CH3OCHO and CH3OCH3 show the strongest correlations in most parameters, and a nearly constant ratio (similar to 1) over a remarkable similar to 9 orders of magnitude in luminosity for the following wide variety of sources: pre-stellar to evolved cores, low- to high-mass objects, shocks, Galactic clouds, and comets. This indicates that COMs chemistry is likely early developed and then preserved through evolved phases. Moreover, the molecular abundances clearly increase with evolution, covering similar to 6 orders of magnitude in the luminosity/mass ratio. We consider CH3OCHO and CH3OCH3 to be most likely chemically linked. They could, for example, share a common precursor, or be formed one from the other. Based on correlations, ratios, and the evolutionary trend, we propose a general scenario for all COMs, involving a formation in the cold, earliest phases of star formation and a following increasing desorption with the progressive thermal and shock-induced heating of the evolving core.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Coletta, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fontani, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Rivilla, V. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mininni, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Colzi, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sanchez-Monge, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Beltran, M. T. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-319523
DOI:	10.1051/0004-6361/202038212
Journal or Publication Title:	Astron. Astrophys.
Volume:	641
Date:	2020
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language GAS-PHASE FORMATION; H-II REGIONS; YOUNG STELLAR OBJECTS; HOT-CORE; RESOLUTION OBSERVATIONS; INTERSTELLAR CLOUDS; BEARING MOLECULES; GRAIN CHEMISTRY; FORMAMIDE; MILLIMETER Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/31952