Oxygen Abundances in Polar Rings -- Chemical Enrichment and Galaxy Evolution

Thursday, February 8, 2024
4:00 PM - 5:00 PM
Trafton North 123

Oxygen Abundances in Polar Rings -- Chemical Enrichment and Galaxy Evolution: Dr. Paul Eskridge
Department of Physics and Astronomy, Minnesota State University - Mankato

Two of the main themes of modern astrophysics are the study of elemental abundances and that of the structural evolution of galaxies. My talk will center on these themes in the context of Polar-Ring Galaxies. These are a curious minority of galaxies that are surrounded by rings of material orbiting nearly perpendicular to the principal plane of the host galaxy.  As such, they present a unique opportunity to study tidal accretion events in systems where the debris is not confused with material from the host.  The polar rings are currently forming stars. This is demonstrated by the existence of gas clouds that are ionized by young, hot stars (HII regions). Spectrophotometry of these HII regions can tell us about the physical state of the gas. In particular, its temperature, electron density, and oxygen abundance.  As oxygen is the most abundant heavy element, it provides us with a means of testing ideas about the origin and stability of polar rings, and, more generally, about the process of galaxy mergers and interactions.