A near-infrared stellar census of blue compact dwarf galaxies: NICMOS detection of red giant stars in the Wolf-Rayet galaxy Markarian 178

We observed the blue compact dwarf/Wolf-Rayet galaxy Mrk 178 with the NICMO S camera aboard Hubble Space Telescope. The galaxy is well resolved into in dividual stars in the near-IR; photometry in J and H yields color-magnitude diagrams containing 791 individual point sources. We discuss the stellar c ontent, drawing particular attention to the intermediate-age and/or old sta rs. Mrk 178 is only the second blue compact dwarf galaxy in which the red g iant branch has been resolved, indicating stars with ages of at least 1-2 G yr. This allows us to derive a distance of greater than or equal to 4.2(+/- 0.5) Mpc. The near-IR color-magnitude diagram also exhibits an abundance of luminous, asymptotic giant branch stars. We find that this requires vigoro us star formation several hundred Myr ago. Some candidate carbon stars are identified via their extreme near-IR color. We argue that Mrk 178 is fundam entally an old galaxy, based on the NICMOS detection of red giants underlyi ng the blue, starburst core, and its extended, faint halo of redder color.