[105.07] Star Formation and the ISM in Four Dwarf Irregular Galaxies

AAS 203rd Meeting, January 2004
Session 105 Dwarf, Irregular, LUM IR and Starburst Galaxies
Oral, Wednesday, January 7, 2004, 2:00-3:30pm, Regency VII

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[105.07] Star Formation and the ISM in Four Dwarf Irregular Galaxies

L. M. Young (New Mexico Tech), L. van Zee (Indiana University), K. Y. Lo (NRAO), R. C. Dohm-Palmer (U. Minnesota), M. E. Beierle (New Mexico Tech/CSU Fresno)

We have used high sensitivity VLA observations of HI in four dwarf galaxies (UGCA 292, GR8, DDO 210, and DDO 216) to study interactions between star formation and the interstellar medium. UGCA 292, GR8, and DDO 210 are shown to contain both warm and cool or cold HI phases; the presence of the cold neutral medium is indicated by a low-dispersion (3--6 km/s) HI component or by the Gauss-Hermite shape parameter h₄ > 0. Contrary to expectations, we find no trend between the incidence of the low-dispersion (colder) phase and the star formation rate in five dwarf galaxies. The colder HI phase may be a necessary ingredient for star formation, but it is clearly not sufficient. However, there is a global trend between the star formation rate of a galaxy andthe incidence of asymmetric HI profiles. This trend probably reflects kinetic energy input from young massive stars.

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