Chemical Evolution of Some Selected Complex Organic Molecules in Low-mass Star-forming Regions

Abstract

The destiny of complex organic molecules (COMs) in star-forming regions is interlinked with various evolutionary phases. Therefore, identifying these species in diversified environments of identical star-forming regions would help to understand their physical and chemical heritage. We identified multiple COMs utilizing the Large Program Astrochemical Surveys At Institut de Radio Astronomie Millimétrique (IRAM) data, dedicated to chemical surveys in Sun-like star-forming regions with the IRAM 30 m telescope. It was an unbiased survey in the millimeter regime, covering the prestellar core, protostar, outflow region, and protoplanetary disk phase. Here, we report the transitions of seven COMs, namely, methanol (CH _3 OH), acetaldehyde (CH _3 CHO), methyl formate (CH _3 OCHO), ethanol (C _2 H _5 OH), propynal (HCCCHO), dimethyl ether (CH _3 OCH _3 ), and methyl cyanide (CH _3 CN) in sources L1544, B1-b, IRAS4A, and SVS13A. We found a trend among these species from the derived abundances using the rotational diagram method and Monte Carlo Markov chain fitting. We have found that the abundances of all of the COMs, except for HCCCHO, increase from the L1544 (prestellar core) and peaks at IRAS16293-2422 (class 0 phase). It is noticed that the abundance of these molecules correlates with the luminosity of the sources. The obtained trend is also visible from the previous interferometric observations and considering the beam dilution effect.

Keywords

• Astrochemistry
• Star forming regions
• Interstellar medium
• Interstellar molecules
• Interstellar abundances