Program: GN-2022A-FT-214

Studies of ubiquitous low-luminosity early-type galaxies are essential for understanding their origin and evolution but remain challenging because of low surface brightness levels. Origin of ultra-diffuse galaxies (UDGs), a sub-class of a low-luminosity stellar system is an important and still unsolved question of galaxy evolution. A sample of 11 extended post-starburst gas-free galaxies with low stellar masses (100 million to 2 billion Msun) has been identified in the Coma cluster and followed-up with ground-based telescopes. According to these findings, these galaxies formed 10-60% of their stars in a recent episode of star formation and will passively evolve into dEs and UDGs in the next 5 Gyr. This phenomenon is truly extraordinary because it suggests that a galaxy can grow substantially in stellar mass over a short period of time without mergers. The most luminous object in the sample, GMP2640 (2.4*10^9 MSun), hosts a strikingly large population of 450+ massive intermediate-age star clusters detected in an archival HST image. We propose to measure a direction of the non-radial stellar age gradient in the disk of GMP2640 to precisely date the quenching epoch and estimate the amount of newly formed stars in the ram pressure induced starburst. This will validate the proposed UDG formation scenario.