The creation of a massive UCD by tidal threshing from NGC 936
Abstract
We study a compact nucleus embedded in an early-type dwarf galaxy, MATLAS-167, which is in the process of disruption by the tidal force of the neighboring giant S0 galaxy, NGC 936, in a group environment. Using the imaging data of the MATLAS survey, we analyze the stellar tidal tail of MATLAS-167 and its central compact nucleus, designated as NGC 936UCD. We find that NGC 936UCD has a luminosity of Mg = -11.430.01 mag and a size of 66.517 pc, sharing the global properties of Ultra Compact Dwarf galaxies (UCDs) but significantly larger and brighter compared to the typical UCD populations observed in the Virgo cluster. By integrating the total luminosity of both the tidal stream and MATLAS-167, we estimate that the disrupted dwarf progenitor possesses a luminosity of Mg = -15.920.06 mag, a typical bright dE luminosity. With the help of the optical spectrum observed by the SDSS survey, we derive the simple stellar population properties of NGC 936UCD: a light-weighted age of 5.60.7 Gyr and metallicity of [Z/H] = -0.830.3 dex. Our findings suggest that tidal threshing is a possible formation mechanism of bright UCD populations in close proximity to giant galaxies.