IC 3475 - A stripped dwarf galaxy in the Virgo cluster

The authors have obtained B and R CCD and H I observations of the Virgo dwarf galaxy IC 3475. The galaxy is remarkable for its very large diameter (≡10 kpc for a Virgo distance modulus of 31) and is comparable in size to the large dwarfs discussed by Sandage and Binggeli. Its light profile is best fitted by an exponential law, characteristic of a dwarf Magellanic irregular galaxy. Despite possessing the photometric structure of a dwarf Magellanic irregular galaxy, IC 3475 contains less than 5.3×106M_sun; of neutral hydrogen. Its hydrogen mass to blue light ratio is less than 0.01, ≡60 times less than the mean value observed for dwarf Magellanic irregulars. It is most likely that IC 3475, which is located near the core of the Virgo cluster, is a stripped dwarf galaxy. The very large size of the galaxy (its diameter is ≡1.8 times larger than that of "normal" dwarfs) appears to rule out evolution of IC 3475 from a normal dwarf irregular or to a normal dwarf elliptical.