The ages of early-type stars: Strömgren photometric methods calibrated, validated, tested, and applied to hosts and prospective hosts of directly imaged exoplanets

Abstract

Age determination is undertaken for nearby early type (BAF) stars, which constitute attractive targets for highcontrast debris disk and planet imaging surveys. Our analysis sequence consists of acquisition of uvbyβ photometry from catalogs, correction for the effects of extinction, interpolation of the photometry onto model atmosphere grids from which atmospheric parameters are determined, and finally, comparison to the theoretical isochrones from pre-main sequence through post-main sequence stellar evolution models, accounting for the effects of stellar rotation. We calibrate and validate our methods at the atmospheric parameter stage by comparing our results to fundamentally determined Teff and log g values. We validate and test our methods at the evolutionary model stage by comparing our results on ages to the accepted ages of several benchmark open clusters (IC 2602, α Persei, Pleiades, Hyades). Finally, we apply our methods to estimate stellar ages for 3493 field stars, including several with directly imaged exoplanet candidates.