HI in the field of the dwarf spheroidal/irregular galaxy Phoenix

Citation
J. St-germain et al., HI in the field of the dwarf spheroidal/irregular galaxy Phoenix, ASTRONOM J, 118(3), 1999, pp. 1235-1244
Citations number
27
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMICAL JOURNAL
ISSN journal
00046256 → ACNP
Volume
118
Issue
3
Year of publication
1999
Pages
1235 - 1244
Database
ISI
SICI code
0004-6256(199909)118:3<1235:HITFOT>2.0.ZU;2-C
Abstract
New results are presented for a mosaic mapping of the H I in the field of t he Local Group dwarf galaxy Phoenix. The observations, obtained with the Au stralia Telescope Compact Array, cover an area of similar to 2 degrees x 2 degrees. Four velocity components are identified, at heliocentric velocitie s of -23, 7, 59, and 140 km s(-1). While the gas at 7 km s(-1) is of Galact ic origin and the gas at 140 km s(-1) is most likely associated with the Ma gellanic Stream, the situation for the two other components is unsure. Howe ver, it is suggested that the component at -23 km s(-1) is probably associa ted with Phoenix because: (1) it has a compact structure and is only slight ly offset from the optical image, (2) its H I mass of similar to 10(5) M. i s what can be expected in such a system, 3) it has a definite velocity grad ient, (4) its location west of Phoenix is compatible with the already suspe cted self-propagation from east to west of the last star formation episode. Because of the large mass (similar to 5 x 10(6) M.) implied if at the dist ance of Phoenix and also because of its large extent, the component at +59 km s(-1) is most likely not associated. Optical velocities are still needed to confirm or not those possible associations.