6-m telescope observations of three dwarf spheroidal galaxies with very low surface brightness

Abstract

Dwarf spheroidal galaxies (dSphs) are mostly investigated in the Local Group. DSphs are difficult targets for observations because of their small size and very low surface brightness. Here we measure spectroscopic and photometric parameters of three candidates for isolated dSphs, KKH? 65 = BTS23, KK 180, and KK 227, outside the Local Group. The galaxies are found to be of low metallicity and low velocity dispersion. They are among the lowest surface brightness objects in the Local Universe. According to the measured radial velocities, metallicities, and structural and photometric parameters, KKH 65 and KK 227 are representatives of the ultra-diffuse quenched galaxies. KKH 65 and KK 227 belong to the outer parts of the groups NGC 3414 and NGC 5371, respectively. KK 180 is located in the Virgo cluster infall region.