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'Missing Link' Clouds in the Southern Galactic Plane Survey


Kavars, DW and Dickey, JM and McClure-Griffiths, NM and Gaensler, BM and Green, AJ, 'Missing Link' Clouds in the Southern Galactic Plane Survey, The Astrophysical Journal, 626, (2) pp. 887-899. ISSN 0004-637X (2005) [Refereed Article]

DOI: doi:10.1086/430296


We present an automated routine to search for H I self-absorption features within the Southern Galactic Plane Survey (SGPS). The data were taken with the Australia Telescope Compact Array (ATCA) and the Parkes Radio Telescope and encompass 3°×105° of sky in the Galactic plane. We apply our routine to this entire region and derive spin temperatures and column densities for 70 of the larger HISA complexes, finding spin temperatures ranging from 6 to 41 K with H I number densities of a few cm -3. These "missing link" clouds fill in the spin temperature and density gaps between dense molecular clouds and diffuse atomic clouds. We compare the H I emission with 12CO emission and find that ∼60% of detected H I self-absorption is correlated in space and in velocity with a molecular counterpart. This is potentially due to a molecular/atomic gas transition. We also compare H I self-absorption with Galactic spiral arms and discuss the possibility of using it as a spiral arm tracer. © 2005. The American Astronomical Society. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Dickey, JM (Professor John Dickey)
ID Code:35909
Year Published:2005
Web of Science® Times Cited:34
Deposited By:Physics
Deposited On:2005-08-01
Last Modified:2006-03-29

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