Journal Article

GSH 006−15+7: a local Galactic supershell featuring transition from H <span class="smallCaps">i</span> emission to absorption

V. A. Moss, N. M. McClure‐Griffiths, R. Braun, A. S. Hill and G. J. Madsen

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 421, issue 4, pages 3159-3169
Published in print April 2012 | ISSN: 0035-8711
Published online April 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.20538.x
GSH 006−15+7: a local Galactic supershell featuring transition from H i emission to absorption

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We report on the discovery of a new Galactic supershell, GSH 006−15+7, from the Galactic All‐Sky Survey data. Observed and derived properties are presented, and we find that GSH 006−15+7 is one of the nearest physically large supershells known, with dimensions of ∼780 × 520 pc at a distance of ∼ 1.5 kpc. The shell wall appears in Hi emission at b≲−6°.5 and in Hi self‐absorption (HiSA) at b≳−6°.5. We use this feature along with HiSA diagnostics to estimate an optical depth of τ∼ 3, a spin temperature of ∼40 K and a swept‐up mass of M∼ 3 × 106 M. We also investigate the origin of GSH 006−15+7, assessing the energy contribution of candidate powering sources and finding evidence in favour of a formation energy of ∼1052 erg. We find that this structure provides evidence for the transfer of mass and energy from the Galactic disc into the halo.

Keywords: radiative transfer; stars: winds, outflows; ISM: bubbles; ISM: structure; Galaxy: structure; radio lines: ISM

Journal Article.  8833 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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