Large diffuse dwarfs in the dynamically cold triple system

TL;DR

This paper reports the discovery of three large diffuse dwarf galaxies in isolated triple systems, highlighting their properties and the intriguing presence of such galaxies in dynamically cold environments.

Contribution

It presents the first identification of large diffuse dwarf galaxies in isolated triple systems and analyzes their properties and dynamics.

Findings

LDD galaxies have diameters of 3.6-10.0 kpc and surface brightness of 26.2-27.3 mag/arcsec^2.

LDD galaxies are found in small, low-velocity-dispersion groups.

Total mass of triplets roughly equals their stellar mass within measurement errors.

Abstract

We report on the discovery of three large diffuse dwarf (LDD) galaxies located in isolated triple systems. They have effective diameters of (3.6-10.0) kpc and effective surface brightness of (26.2--27.3)$^m/$sq.arcsec. We note that the LDD galaxies tend to occur in small groups with a very low dispersion of radial velocities. The total (orbital) mass of the triplets approximately equals to their integral stellar mass within velocity measurement errors. The presence of LDD galaxies in cold multiple systems seems mysterious.