WHAM Discovery of a New Superbubble in Circinus

Type Conference Paper
Names Martin Gostisha, R. A. Benjamin, L. M. Haffner
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #217, #251.08
Volume 43
Date January 1, 2011
URL http://adsabs.harvard.edu/abs/2011AAS...21725108G
Library Catalog NASA ADS
Abstract We present a Wisconsin H-alpha Mapper (WHAM) survey of the fourth quadrant of the Galactic plane in diffuse emission from [S II] 6716 A, covering Galactic longitude l=270-360 degrees and latitude |b|<12 degrees. One of the more prominent features seen is a large-scale ionized bubble, centered at l=320.0 deg, b=3.4 deg with a diameter of 7 degrees. Spectra of the center of this region shows line splitting characteristic of an expanding bubble. A search for high mass star in the region shows that this bubble subtends over 40 O stars, including the cluster Pismis 20 which is part of the Circinus OB association. Assuming that the bubble is at the distance of this cluster, yields a bubble diameter of 300 parsec. When this is combined with the measured expansion velocity of 7 km/s, we derive a bubble age of approximately 2 Myrs, consistent with the estimated age of the Circinus OB association. We discuss the energetics of the bubble as well as the result of searching for this bubble using tracers at other wavelengths. This research was supported the NSF REU site grant to the University of Wisconsin-Madison.
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