A high-velocity cloud impact forming a supershell in the Milky Way

Journal Article · Sat Aug 20 04:00:00 EDT 2016 · Astrophysical Journal Letters

DOI:https://doi.org/10.3847/2041-8205/827/2/L27· OSTI ID:22868765

Park, Geumsook; Koo, Bon-Chul ^[1]; Kang, Ji-hyun ^[2]; Gibson, Steven J. ^[3]; Peek, J. E. G. ^[4]; Douglas, Kevin A. ^[5]; Korpela, Eric J. ^[6]; Heiles, Carl E. ^[7]

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1. Department of Physics and Astronomy, Seoul National University Seoul 151-747 (Korea, Republic of)
2. Korea Astronomy and Space Science Institute Daejeon 305-348 (Korea, Republic of)
3. Department of Physics and Astronomy, Western Kentucky University 1906 College Heights Blvd., Bowling Green, KY 42101 (United States)
4. Space Telescope Science Institute 3700 San Martin Dr., Baltimore, MD 21218 (United States)
5. Department of Physics and Astronomy, Okanagan College 1000 K. L. O. Rd., Kelowna, British Columbia V1Y 4X8 (Canada)
6. Space Sciences Laboratory, University of California Berkeley, CA 94720 (United States)
7. Radio Astronomy Lab, UC Berkeley 601 Campbell Hall, Berkeley, CA 94720 (United States)

Neutral atomic hydrogen (H i) gas in interstellar space is largely organized into filaments, loops, and shells, the most prominent of which are “supershells.” These gigantic structures, which require ≳ 3× 10{sup 52} erg to form, are generally thought to be produced by either the explosion of multiple supernovae (SNe) in OB associations or, alternatively, by the impact of high-velocity clouds (HVCs) falling into the Galactic disk. Here, we report the detection of a kiloparsec (kpc)-size supershell in the outskirts of the Milky Way with the compact HVC 040 + 01−282 (hereafter, CHVC040) at its geometrical center using the “Inner-Galaxy Arecibo L-band Feed Array” H i 21 cm survey data. The morphological and physical properties of both objects suggest that CHVC040, which is either a fragment of a nearby disrupted galaxy or a cloud that originated from an intergalactic accreting flow, collided with the disk ∼5 Myr ago to form the supershell. Our results show that some compact HVCs can survive their trip through the Galactic halo and inject energy and momentum into the Milky Way disk.

• OSTI ID: 22868765
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 827; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DETECTION
EXPLOSIONS
HYDROGEN
INTERSTELLAR SPACE
MILKY WAY
PHYSICAL PROPERTIES
PLANET-SYSTEM ACCRETION
SHELLS
SUPERNOVAE