The Bulletin of The Korean Astronomical Society (천문학회보)

The Korean Astronomical Society (한국천문학회)
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A High-Velocity Cloud Impact Forming a Supershell in the Milky Way

  • Park, Geumsook (Department of Physics and Astronomy, Seoul National University) ;
  • Koo, Bon-Chul (Department of Physics and Astronomy, Seoul National University) ;
  • Kang, Ji-hyun (Korea Astronomy and Space Science Institute) ;
  • Gibson, Steven J. (Department of Physics and Astronomy, Western Kentucky University) ;
  • Peek, J.E.G. (Space Telescope Science Institute) ;
  • Douglas, Kevin A. (Department of Physics and Astronomy, Okanagan College) ;
  • Korpela, Eric J. (Space Sciences Laboratory, University of California Berkeley) ;
  • Heiles, Carl E. (Radio Astronomy Lab)
  • Published : 2016.10.12
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Abstract

We report the discovery of a kiloparsec-size supershell in the outskirts of the Milky Way with the compact high-velocity cloud, HVC 040+01-282 (hereafter, CHVC040), at its geometrical center using the "Inner-Galaxy Arecibo L-band Feed Array" HI 21 cm survey data. Supershells are large gaseous shells, which could be produced by one of most energetic activities with an explosion energy more than $3{\times}1052erg$. The most promising origin is the explosion of multiple supernovae in OB associations, or alternatively, the impact of HVCs falling into the Galactic disk. We found the association between CHVC040 and the Galactic supershell by analysis of their morphological and physical properties. Our results imply that some compact HVCs can survive their trip through the Galactic halo and inject energy and momentum into the Milky Way disk.

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