A HIGH-VELOCITY CLOUD IMPACT FORMING A SUPERSHELL IN THE MILKY WAY

作者：Park Geumsook^*; Koo Bon Chul; Kang Ji hyun; Gibson Steven J; Peek J E G; Douglas Kevin A; Korpela Eric J; Heiles Carl E

来源：Astrophysical Journal Letters, 2016, 827(2): L27.

DOI：10.3847/2041-8205/827/2/L27

• Galaxy: disk
• ISM: clouds
• radio lines: ISM

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 greater than or similar to 3 x 10(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 similar to 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.

• 出版日期2016-8-20