The carbon inventory in a quiescent, filamentary molecular cloud in g328

Michael G. Burton, Michael C.B. Ashley, Catherine Braiding, John W.V. Storey, Craig Kulesa, David J. Hollenbach, Mark Wolfire, Christian Glück, Gavin Rowell

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

We present spectral line images of [C I] 809 GHz, CO J = 1-0 115 GHz and H I 1.4 GHz line emission, and calculate the corresponding C, CO and H column densities, for a sinuous, quiescent giant molecular cloud about 5 kpc distant along the l = 328° sightline (hereafter G328) in our Galaxy. The [C I] data comes from the High Elevation Antarctic Terahertz telescope, a new facility on the summit of the Antarctic plateau where the precipitable water vapor falls to the lowest values found on the surface of the Earth. The CO and H I data sets come from the Mopra and Parkes/ATCA telescopes, respectively. We identify a filamentary molecular cloud, 75 × 5 pc long with mass 4 × 10 4 M and a narrow velocity emission range of just 4 km s-1. The morphology and kinematics of this filament are similar in CO, [C I], and H I, though in the latter appears as self-absorption. We calculate line fluxes and column densities for the three emitting species, which are broadly consistent with a photodissociation region model for a GMC exposed to the average interstellar radiation field. The [C/CO] abundance ratio averaged through the filament is found to be approximately unity. The G328 filament is constrained to be cold (T Dust < 20 K) by the lack of far-IR emission, to show no clear signs of star formation, and to only be mildly turbulent from the narrow line width. We suggest that it may represent a GMC shortly after formation, or perhaps still in the process of formation.

Original languageEnglish (US)
Article number72
JournalAstrophysical Journal
Volume782
Issue number2
DOIs
StatePublished - Feb 20 2014
Externally publishedYes

Keywords

  • ISM: abundances
  • ISM: clouds
  • ISM: molecules
  • ISM: structure
  • Radio lines: ISM
  • Telescopes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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