The Distance to the Galaxy Coma P

Abstract

If the extremely low surface-brightness galaxy Coma P lies at 5.5 ± 0.3 Mpc, as recently proposed, then it would have an extraordinarily deviant peculiar velocity of ∼900 km s^-1 at a location where differential velocities between galaxies are low. We have accessed the images from the Hubble Space Telescope (HST) archives used to derive the literature distance from the magnitude of the tip of the red giant branch. Our analysis gives the distance to be 10.9 ± 1.0 Mpc. At this location the galaxy lies within the infall region of the Virgo Cluster, such that its still considerable peculiar velocity of ∼500 km s^-1 is consistent with an established model. Coma P has an unusually pronounced asymptotic giant branch (AGB) relative to its red giant branch. The dominant stellar population is just a few Gyr old.