The Absolute Age of NGC 3201 derived from Detached Eclipsing Binaries and the Hess Diagram

Abstract

We estimate the absolute age of the globular cluster NGC 3201 using $10,000$ sets of theoretical isochrones constructed through Monte Carlo simulation using the Dartmouth Stellar Evolution Program. These isochrones take into consideration of uncertainty introduced by the choice of stellar evolution parameters. We fit isochrones with 3 detached eclipsing binaries and obtained an age independent of distance. We also fit isochrones with differential reddening corrected HST photometry data utilizing two different Hess diagram based fitting methods. Results from 3 different methods analyzing 2 different types of data agree to within $1 \sigma$, and we find the absolute age of NGC 3201 $= 11.85 \pm 0.74$ Gyr. We also perform variable importance analysis to study the uncertainty contribution from individual parameters and we find the distance is the dominance source of uncertainty in photometry based analysis while total metallicity, Helium abundance, $\alpha$-element abundance, mixing length, and treatment of helium diffusion are important source of uncertainties for all 3 methods.