A survey for low surface brightness galaxies around M31. I. The newly discovered dwarf andromeda V

We present B-, V-, and I-band images, as well as an Hα image, of Andromeda VI (And VI). This is the second newly identified dwarf spheroidal (dSph) companion to M31 found using a digital filtering technique applied to the second Palomar Sky Survey for which about 1550 deg2 now have been surveyed. And VI was confirmed to be a nearby dSph galaxy when it resolved into stars easily with a short V-band exposure with the 4 m telescope. Subarcsecond images taken at the Kitt Peak WIYN 3.5 m telescope provided (I, V-I) and (V, B-V) color-magnitude diagrams that yield a distance of 775 ± 35 kpc using the tip of the red giant branch method, and a mean metallicity of [Fe/H] = -1.58 ± 0.20 with a dispersion of approximately 0.3 dex. And VI has a galactocentric distance of roughly 271 kpc and MV = -11.3. All observed properties of And VI are consistent with its classification as a dSph companion to M31. Despite the recent identification of the And V, And VI, and Cas dwarfs, the Local Group luminosity function remains highly deficient in faint galaxies relative both to CDM simulations of its formation, and to the luminosity functions for richer clusters of galaxies.

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