On aging star clusters using red supergiants independent of the fraction
  of interacting binary stars
  We use the Binary Population and Spectral Synthesis (BPASS) models to test
the recent suggestion that red supergiants can provide an accurate age estimate
of a co-eval stellar population that is unaffected by interacting binary stars.
Ages are estimated by using both the minimum luminosity red supergiant and the
mean luminosity of red supergiants in a cluster. We test these methods on a
number of observed star clusters and find our results in agreement with
previous estimates. Importantly we find the difference between the ages derived
from stellar population models with and without a realistic population of
interacting binary stars is only a few 100,000 years at most. We find that the
mean luminosity of red supergiants in a cluster is the best method to determine
the age of a cluster because it is based o the entire red supergiant population
rather than using only the least luminous red supergiant.
