A Gaseous Group with Unusual Remote Star Formation

作者：Santiago Figueroa N^*; Putman M E; Werk J; Meurer G R; Ryan Weber E

来源：Publications of the Astronomical Society of Australia, 2011, 28(3): 271-279.

DOI：10.1071/AS11008

• galaxies: ISM
• galaxies: dwarf
• HII regions
• ISM: HI

We present VLA 21-cm observations of the spiral galaxy ESO 481-G017 to determine the nature of remote star formation traced by an HII region found 43 kpc and similar to 800 km s(-1) from the galaxy center (in projection). ESO 481-G017 is found to have a 120 kpc HI disk with a mass of 1.2 x 10(10) M-circle dot and UV GALEX images reveal spiral arms extending into the gaseous disk. Two dwarf galaxies with HI masses close to 10(8) M-circle dot are detected at distances of similar to 200 kpc from ESO 481-G017 and a HI cloud with a mass of 6 x 10(7) M-circle dot is found near the position and velocity of the remote HII region. The HII region is somewhat offset from the HI cloud spatially and there is no link to ESO 481-G017 or the dwarf galaxies. We consider several scenarios for the origin of the cloud and HII region and find the most likely is a dwarf galaxy that is undergoing ram pressure stripping. The HI mass of the cloud and H alpha luminosity of the HII region (10(38.1) erg s(-1)) are consistent with dwarf galaxy properties, and the stripping can trigger the star formation as well as push the gas away from the stars.

• 出版日期2011