RESOLVING VEGA AND THE INCLINATION CONTROVERSY WITH CHARA/MIRC

Optical and infrared interferometers definitively established that the photometric standard Vega (=α Lyrae) is a rapidly rotating star viewed nearly pole-on. Recent independent spectroscopic analyses could not reconcile the inferred inclination angle with the observed line profiles, preferring a larger inclination. In order to resolve this controversy, we observed Vega using the six-beam Michigan Infrared Combiner on the Center for High Angular Resolution Astronomy Array. With our greater angular resolution and dense (u, v)-coverage, we find that Vega is rotating less rapidly and with a smaller gravity darkening coefficient than previous interferometric results. Our models are compatible with low photospheric macroturbulence and are also consistent with the possible rotational period of ∼0.71 days recently reported based on magnetic field observations. Our updated evolutionary analysis explicitly incorporates rapid rotation, finding Vega to have a mass of 2.15+0.10–0.15 M☉ and an age 700–75+150 Myr, substantially older than previous estimates with errors dominated by lingering metallicity uncertainties (Z = 0.006+0.003–0.002).