The H i Content of the Local Group Dwarf (Spheroidal or Irregular?) Galaxy PHOENIX
Abstract
Neutral hydrogen was detected in the Local Group dwarf galaxy Phoenix. The 21 cm H I line emission, observed at a heliocentric radial velocity of 56 km s^-1^, is clearly separated from a much larger scale component at ~140 km s^-1^ which was previously associated with the Magellanic Stream. The profile width {DELTA}V_50_~ 21 km s^-1^, combined with the high inclination of the system, suggests that not much rotation is present in this system which would then be mainly supported by turbulent motions. Using a newly determined distance estimate, the integrated profile gives a total H I mass of ~1.0 x 10^5^ M_sun_ for an M_H I_/L_V_~0.07 M_sun_/L_sun_. Most of the known properties of Phoenix imply that it is intermediate between typical dwarf irregular and dwarf spheroidal galaxies. It is suggested that, in fact, the two types of galaxies may belong to the same class of objects having a different history of star formation.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1991
- DOI:
- 10.1086/186185
- Bibcode:
- 1991ApJ...381L..13C
- Keywords:
-
- Dwarf Galaxies;
- Galactic Evolution;
- Galactic Structure;
- Irregular Galaxies;
- Local Group (Astronomy);
- Charge Coupled Devices;
- Emission Spectra;
- Hydrogen;
- Neutral Gases;
- Star Formation;
- Astrophysics;
- GALAXIES: INTERNAL MOTIONS;
- GALAXIES: INTERSTELLAR MATTER;
- RADIO SOURCES: 21 CM RADIATION