Distance to the Dorado Group

Abstract

Based on the archival images of the Hubble Space Telescope, stellar photometry of the brightest galaxies of the Dorado group: NGC 1433, NGC 1533, NGC 1566 and NGC 1672 was carried out. Red giants were found on the obtained CM diagrams and distances to the galaxies were measured using the TRGB method. The obtained values: $14.2\pm 1.2$, $15.1\pm 0.9$, $14.9 \pm 1.0$ and $15.9\pm 0.9$~Mpc, show that all the named galaxies are located approximately at the same distances and form a scattered group with an average distance $D = 15.0$ Mpc. It was found that blue and red supergiants are visible in the hydrogen arm between the galaxies NGC 1533 and IC 2038, and form a ring structure in the lenticular galaxy NGC 1533, at a distance of 3.6 kpc from the center. The high metallicity of these stars ($Z = 0.02$) indicates their origin from NGC 1533 gas.