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

TL;DR

This study presents spectroscopic and photometric analysis of three low surface brightness dwarf spheroidal galaxy candidates outside the Local Group, revealing their low metallicity, low velocity dispersion, and classification as ultra-diffuse quenched galaxies.

Contribution

First detailed spectroscopic and photometric characterization of isolated low surface brightness dwarf spheroidal candidates outside the Local Group.

Findings

KKH65 and KK227 are ultra-diffuse quenched galaxies.

All three galaxies have very low metallicity and velocity dispersion.

KK180 is located in the Virgo cluster infall region.

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, KKH65=BTS23, KK180, and KK227, 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, KKH65 and KK227 are representatives of the ultra-diffuse quenched galaxies. KKH65 and KK227 belong to the outer parts of the groups NGC3414 and NGC5371, respectively. KK180 is located in the Virgo cluster infall region.