SDSSJ124155.33+114003.7 -- a Missing Link Between Compact Elliptical and Ultracompact Dwarf Galaxies

TL;DR

This paper reports the discovery of a compact object that bridges the gap between compact ellipticals and ultracompact dwarf galaxies, providing insights into galaxy evolution and tidal stripping processes.

Contribution

The study identifies a unique compact object with properties linking UCDs and compact ellipticals, highlighting a possible evolutionary pathway.

Findings

The object has a blue core and a redder envelope with specific stellar age and metallicity.

It lies between UCDs and compact ellipticals on the Fundamental Plane.

Its properties suggest it is a tidally stripped low-luminosity elliptical or lenticular galaxy.

Abstract

We report the discovery of a compact object (R_e = 32 pc, M_B = -12.34 mag) at a projected distance of 9 kpc from Messier 59, a giant elliptical in the Virgo cluster. Using HST imaging and SDSS spectroscopy, both available in the Virtual Observatory, we find that this object has a blue core containing one-quarter of the light, and a redder n=1 Sersic envelope, as well as luminosity-weighted age of 9.3 +/- 1.4 Gyr, a metallicity of -0.03 +/- 0.04 dex and a velocity dispersion of 48 +/- 5 km/s. While ultra-compact dwarfs (UCDs) in the face-on view of the Fundamental Plane are found to form a sequence connecting the highest-luminosity globular clusters with the lowest-luminosity dwarf ellipticals, the compact object near M59 lies in between this UCD sequence and the positions of compact ellipticals. Its stellar age, metallicity, and effective surface brightness are similar to low-luminosity ellipticals and lenticulars, suggesting that SDSSJ124155.33+114003.7 is a result of the tidal stripping of such an object.