Discovery of ongoing star formation in red and presumably dead galaxies: Implications for galaxy evolution

Abstract: Textbooks tell us that elliptical and lenticular (S0 type) galaxies are red and featureless because they lack young blue stars and have stopped forming stars long time in the past. The physical causes that led to this so called "quenching" of star formation and the fact that the quiescence is being maintained in these galaxies is the subject of intense study today. However, recent survey of the sky in ultraviolet wavelengths, taken with satellite GALEX, have revealed that a significant fraction of these red and presumably dead galaxies are actually producing stars at low levels. I will discuss what these exceptions from the rule can tell us about the processes that shape galaxy evolution in general.

Samir Salim
Department of Astronomy
Indiana University