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CoCCoA: Complex Chemistry in hot Cores with ALMA. Selected oxygen-bearing species

Publikation: Working paper/Preprint › Preprint

Dokumenter

  • Y. Chen
    • ,
  • M. L. van Gelder
    • ,
  • P. Nazari
    • ,
  • C. L. Brogan
    • ,
  • E. F. van Dishoeck
    • ,
  • H. Linnartz
    • ,
  • J. K. Jørgensen
    • ,
  • T. R. Hunter
    • ,
  • O. H. Wilkins
    • ,
  • G. A. Blake
    • ,
  • P. Caselli
    • ,
  • K. -J. Chuang
    • ,
  • C. Codella
    • ,
  • I. Cooke
    • ,
  • M. N. Drozdovskaya
    • ,
  • R. T. Garrod
    • ,
  • S. Ioppolo
  • M. Jin
    • ,
  • B. M. Kulterer
    • ,
  • N. F. W. Ligterink
    • ,
  • A. Lipnicky
    • ,
  • R. Loomis
    • ,
  • M. G. Rachid
    • ,
  • S. Spezzano
    • ,
  • B. A. McGuire
Complex organic molecules (COMs) have been observed to be abundant in the gas phase toward protostars. Deep line surveys have been carried out only for a limited number of well-known high-mass star forming regions using the Atacama Large Millimeter/submillimeter Array (ALMA), which has unprecedented resolution and sensitivity. Statistical studies on oxygen-bearing COMs (O-COMs) in high-mass protostars using ALMA are still lacking. With the recent CoCCoA survey, we are able to determine the column density ratios of six O-COMs with respect to methanol (CH$_3$OH) in a sample of 14 high-mass protostellar sources to investigate their origin through ice and/or gas-phase chemistry. The selected species are: acetaldehyde (CH$_3$CHO), ethanol (C$_2$H$_5$OH), dimethyl ether (DME, CH$_3$OCH$_3$), methyl formate (MF, CH$_3$OCHO), glycolaldehyde (GA, CH$_2$OHCHO), and ethylene glycol (EG, (CH$_2$OH)$_2$). DME and MF have the highest and most constant ratios within one order of magnitude, while the other four species have lower ratios and exhibit larger scatter by 1-2 orders of magnitude. We compare the O-COM ratios of high-mass CoCCoA sources with those of 5 low-mass protostars available from the literature, along with the results from experiments and simulations. We find that the O-COM ratios with respect to methanol are on the same level in both the high- and low-mass samples, which suggests that these species are mainly formed in similar environments during star formation, probably in ice mantles on dust grains during early pre-stellar stages. Current simulations and experiments can reproduce most observational trends with a few exceptions, and hypotheses exist to explain the differences between observations and simulations/experiments, such as the involvement of gas-phase chemistry and different emitting areas of molecules.
OriginalsprogEngelsk
StatusUdgivet - okt. 2023

    Forskningsområder

  • astro-ph.GA

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