RESOLVING VEGA AND THE INCLINATION CONTROVERSY WITH CHARA/MIRC

Optical and infrared interferometers definitively established that the photometric standard Vega (= alpha 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 similar to 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(-0.15) (+0.10) M-circle dot and an age 700(+150) (-75) Myr, substantially older than previous estimates with errors dominated by lingering metallicity uncertainties (Z = 0.006(-0.002) (+ 0.003)).