Mass-Models of Five Nearby Dwarf Irregular Galaxies

Abstract

Five nearby dwarf irregular galaxies, amongst the recently surveyed dwarf members of the Sculptor and Centaurus A groups (at 2.5 Mpc and 3.5 Mpc), have been imaged in neutral hydrogen (HI) with the Australia Telescope and the Very Large Array. These objects have absolute magnitudes M_B in the range -14.9 to -12.7, yet they are clearly rotationally supported, with maximum rotation velocities ranging from 43 km/s to 67 km/s. Multi-component mass-models have been fitted to the rotation curves. We investigate the properties of their dark matter halos, and the scaling laws of the dark matter halos parameters.

Postscript file (8 pages including 4 figures). To appear in "Dark and Visible Matter in Galaxies and Cosmological Implications" (Sesto Pusteria, Italy, 2-5 July 1996), ASP Conference Series, eds M.Persic and P.Salucci