Brian Chaboyer coauthored work using ages of old stellar clusters to constrain cosmic history. The analysis combines stellar-evolution calculations, distance estimates and uncertainty in when the clusters formed, then compares the resulting age bounds with cosmological expansion models.[ref]
New Globular Cluster Age Estimates and Constraints on the Cosmic Equation of State and The Matter Density of the Universe by Lawrence M. Krauss and Brian Chaboyer. Abstract: cluster ages, distance uncertainties and cosmological constraints
The comparison is useful because the universe must be older than its stars. It nevertheless requires the cluster's inferred stellar age and the delay before cluster formation to be distinguished.
New to topics? Read the docs here!