A high-resolution study of the H I-H 2 transition across the perseus molecular cloud

Download
  1. Get@NRC: A high-resolution study of the H I-H 2 transition across the perseus molecular cloud (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1088/0004-637X/748/2/75
AuthorSearch for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for:
TypeArticle
Journal titleThe Astrophysical Journal
ISSN0004-637X
Volume748
Issue2
Article number75
AbstractTo investigate the fundamental principles of H 2 formation in a giant molecular cloud, we derive the H I and H 2 surface density (Σ H I and Σ H2) images of the Perseus molecular cloud on sub-pc scales (0.4pc). We use the far-infrared data from the Improved Reprocessing of the IRAS Survey and the V-band extinction image provided by the COMPLETE Survey to estimate the dust column density image of Perseus. In combination with the H I data from the Galactic Arecibo L-band Feed Array H I Survey and an estimate of the local dust-to-gas ratio, we then derive the Σ H2 distribution across Perseus. We find a relatively uniform Σ H I6-8 Mpc -2 for both dark and star-forming regions, suggesting a minimum H I surface density required to shield H 2 against photodissociation. As a result, a remarkably tight and consistent relation is found between Σ H2/Σ H I and Σ H I + Σ H2. The transition between the H I- and H 2-dominated regions occurs at N(H I) + 2N(H 2) (8-14)× 10 20cm -2. Our findings are consistent with predictions for H 2 formation in equilibrium, suggesting that turbulence may not be of primary importance for H 2 formation. However, the importance of a warm neutral medium for H 2 shielding, an internal radiation field, and the timescale of H 2 formation still remain as open questions. We also compare H 2 and CO distributions and estimate the fraction of "CO-dark" gas, f DG 0.3. While significant spatial variations of f DG are found, we do not find a clear correlation with the mean V-band extinction. © 2012. The American Astronomical Society. All rights reserved..
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Herzberg Institute of Astrophysics (HIA-IHA)
Peer reviewedYes
NPARC number21269513
Export citationExport as RIS
Report a correctionReport a correction
Record identifier24219958-a3cb-4e6f-bddd-c2e89e21467a
Record created2013-12-12
Record modified2016-07-18
Bookmark and share
  • Share this page with Facebook (Opens in a new window)
  • Share this page with Twitter (Opens in a new window)
  • Share this page with Google+ (Opens in a new window)
  • Share this page with Delicious (Opens in a new window)
Date modified: