The Age and Helium Abundance of the Galactic Bulge
Australian National University
I discuss the ongoing issue of the age and helium abundance of the Galactic bulge stellar population and summerise historical and recent attempts to measure these two values. I discuss how the age and heliumabundance of a stellar population can be degenerate observationally, and thus how unstated assumptions of the helium-metallicity relation can result in biased age-metallicity determinations. Finally, I present efforts to tackle this degeneracy using chemical evolution models, forward modelling of observational selection effects using Galactic-structure-based microlensing models, and upcoming mass measurements of detached red giant eclipsing binary twins. I make the case that the degeneracy between these two parameters can be resolved with currently available instrumentation and software, and both of these fundamental parameters of Galactic history can be measured to 1 part in 10 or better in the near future.
Date: Wednesday, 11 December 2013 Time: 13:00 Where: McGill University Ernest Rutherford Physics Building, R.E. Bell Conference Room (room 103) Contact: Robert Rutledge