The dwarf spheroidal galaxy DDO 44: stellar populations and distance

I. D. Karachentsev, M. E. Sharina, E. K. Grebel, A. E. Dolphin, D. Geisler, P. Guhathakurta, P. W. Hodge, V. E. Karachentseva, A. Sarajedini, P. Seitzer

Published 1999-10-21Version 1

We present ground-based and HST WFPC2 imaging of the nearby low surface brightness dwarf spheroidal galaxy DDO 44. For the first time DDO 44 was resolved into stars. The resulting color-magnitude diagram for about 1290 stars shows the red giant branch with a tip at I=(23.55+-0.15) mag, which yields a distance of (3.2+-0.2) Mpc consistent with membership of DDO 44 in the NGC 2403 group. The linear separation of DDO 44 from NGC 2403 is 75 kpc on the sky and (30+-450) kpc along the line of sight. The relationship between the dwarf galaxy's absolute R magnitude of -13.1 mag, its central surface brightness of 24.1 mag/square arcsec, and its mean metallicity of -1.7 dex follow the trend for other nearby dwarf spheroidal galaxies. One globular cluster candidate has also been identified in DDO 44.