skip to main content

Title: Organic species in infrared dark clouds

It is currently assumed that infrared dark clouds (IRDCs) represent the earliest evolutionary stages of high-mass stars (>8 M {sub ☉}). Submillimeter and millimeter-wave studies performed over the past 15 yr show that IRDCs possess a broad variety of properties, and hence a wide range of problems and questions that can be tackled. In this paper, we report an investigation of the molecular composition and chemical processes in two groups of IRDCs. Using the Mopra, APEX, and IRAM radio telescopes over the last four years, we have collected molecular line data for CO, H{sub 2}CO, HNCO, CH{sub 3}CCH, CH{sub 3}OH, CH{sub 3}CHO, CH{sub 3}OCHO, and CH{sub 3}OCH{sub 3}. For all of these species we estimated molecular abundances. We then undertook chemical modeling studies, concentrating on the source IRDC028.34+0.06, and compared observed and modeled abundances. This comparison showed that to reproduce observed abundances of complex organic molecules, a zero-dimensional gas-grain model with constant physical conditions is not sufficient. We achieved greater success with the use of a warm-up model, in which warm-up from 10 K to 30 K occurs following a cold phase.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States)
  2. Max Planck Institute for Astronomy (MPIA), Königstuhl 17, D-69117 Heidelberg (Germany)
  3. Australia Telescope National Facility, CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia)
  4. Department of Physics and Astronomy, Macquarie University, NSW 2109 (Australia)
  5. Institute of Applied Physics of the Russian Academy of Sciences, Ulyanova 46, 603950 Nizhny Novgorod (Russian Federation)
  6. European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Santiago 19 (Chile)
Publication Date:
OSTI Identifier:
22348300
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; CARBON MONOXIDE; COMPARATIVE EVALUATIONS; INFRARED RADIATION; MASS; METHANOL; MOLECULES; RADIO TELESCOPES; STARS