Resolving Vega and the Inclination Controversy with CHARA/MIRC
Abstract
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).
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2012
- DOI:
- arXiv:
- arXiv:1211.6055
- Bibcode:
- 2012ApJ...761L...3M
- Keywords:
-
- infrared: stars;
- stars: individual: Vega;
- stars: rotation;
- techniques: interferometric;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted for publication in ApJ Letters
