Distances to 18 Dwarf Galaxies from the Arecibo Survey

Abstract: Based on the archival Hubble Space Telescope images, we have performed stellar photometry for 18 dwarf galaxies. Branches of young and old stars are seen on the constructed Hertzsprung-Russell diagrams. Using the photometry of red giants and applying the TRGB method, we have determined accurate distances for all 18 galaxies for the first time. The galaxies AGC238890 and AGC747826 have minimum ($D$ = 5.1 Mpc) and maximum ($D$ = 12.0 Mpc) distances, respectively. The distances to the remaining galaxies lie within this range. Low-metallicity galaxies have been identified by measuring the color indices of the red giant branch: AGC102728, AGC198691, AGC205590, AGC223231, AGC731921, and AGC747826. We have determined the distance to AGC198691 with a record low metallicity. Since AGC223254, AGC229053, AGC229379, AGC238890, AGC731921, and AGC742601 are projected onto the Virgo cluster of galaxies, the distances estimated by us together with the velocities of these galaxies measured previously at Arecibo can be used to refine the effect of galaxy infall to the Virgo cluster.