Resolving Vega and the inclination controversy with CHARA/MIRC
ten Brummelaar, T
Astrophysical Journal Letters
American Astronomical Society / IOP Publishing
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).
The CHARA Array is currently funded by the National Science Foundation through AST-1211929 and by the Georgia State University. Funding for the MIRC combiner came from the University of Michigan, and observations were supported through NSF grants AST-0352723, AST-0707927, and AST-1108963. S.T.R. acknowledges partial support from NASA grant NNH09AK731. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France, and NASA’s Astrophysics Data System (ADS) Bibliographic Services.
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.
Vol. 761, no.1