A new isolated dSph galaxy near the Local Group

Abstract

Observations of the highly isolated dwarf spheroidal galaxy KKs 3 = [KK2000] 03 with the Hubble Space Telescope Advanced Camera for Surveys are presented. We measured the galaxy distance of 2.12 ± 0.07 Mpc using the tip of red giant branch method. The total blue absolute magnitude of the galaxy is estimated as M_B = -10.8 mag. We briefly discuss the star formation history of KKs 3 derived from its colour-magnitude diagram. According to our calculation, the total stellar mass of the galaxy is 2.3 × 10⁷ M_⊙, and most stars (74 per cent) were formed at an early epoch more than 12 Gyr ago. A full description of the properties of the colour-magnitude diagram requires some extension of star formation in metallicity and age.