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The 'Carina Flare' supershell: probing the atomic and molecular ISM in a galactic chimney


Dawson, JR and Mizuno, N and Onishi, T and McClure-Griffiths, NM and Fukui, Y, The 'Carina Flare' supershell: probing the atomic and molecular ISM in a galactic chimney, Monthly Notices of the Royal Astronomical Society, 387, (February) pp. 31-44. ISSN 1365-2966 (2008) [Refereed Article]

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DOI: doi:10.1111/j.1365-2966.2008.13152.x


The "Carina Flare" supershell, GSH 287+04-17, is a molecular supershell originally discovered in 12CO(J=1-0) with the NANTEN 4m telescope. We present the first study of the shell's atomic ISM, using HI 21 cm line data from the Parkes 64m telescope Southern Galactic Plane Survey. The data reveal a gently expanding, ~ 230 x 360 pc HI supershell that shows strong evidence of Galactic Plane blowout, with a break in its main body at z ~ 280 pc and a capped high-latitude extension reaching z ~ 450 pc. The molecular clouds form co-moving parts of the atomic shell, and the morphology of the two phases reflects the supershell's influence on the structure of the ISM. We also report the first discovery of an ionised component of the supershell, in the form of delicate, streamer-like filaments aligned with the proposed direction of blowout. The distance estimate to the shell is re-examined, and we find strong evidence to support the original suggestion that it is located in the Carina Arm at a distance of 2.6 0.4 kpc. Associated HI and H2 masses are estimated as M(HI) ~ 7 3 x 10 5 Msol and M(H2) ~ 2.0 0.6 x 10 5 Msol, and the kinetic energy of the expanding shell as E ~ 1 x 10 51 erg. We examine the results of analytical and numerical models to estimate a required formation energy of several 10 51 to ~ 10 52 erg, and an age of ~ 10 7 yr. This age is compatible with molecular cloud formation time-scales, and we briefly consider the viability of a supershell-triggered origin for the molecular component.

Item Details

Item Type:Refereed Article
Keywords:ISM: atoms; ISM: bubbles; ISM: evolution; ISM: molecules; ISM: structure; Galaxy: structure
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:Dawson, JR (Dr Joanne Dawson)
ID Code:74986
Year Published:2008
Web of Science® Times Cited:19
Deposited By:Mathematics and Physics
Deposited On:2011-12-22
Last Modified:2012-02-07

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