Reference : First Results from the CHARA Array. VII. Long-Baseline Interferometric Measurements o...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/19318
First Results from the CHARA Array. VII. Long-Baseline Interferometric Measurements of Vega Consistent with a Pole-On, Rapidly Rotating Star
English
Aufdenberg, J. P. [Michelson Postdoctoral Fellow.; National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719.]
Mérand, A. [LESIA, UMR 8109, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France.]
Coudé du Foresto, V. [LESIA, UMR 8109, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France.]
Absil, Olivier mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS) >]
Di Folco, E. [LESIA, UMR 8109, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France.]
Kervella, P. [LESIA, UMR 8109, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France.]
Ridgway, S. T. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719.; LESIA, UMR 8109, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France.]
Berger, D. H. [Department of Astronomy, University of Michigan, 917 Dennison Building, 500 Church Street, Ann Arbor, MI 48109-1042.; CHARA Array, Mount Wilson Observatory, Mount Wilson, CA 91023.]
ten Brummelaar, T. A. [CHARA Array, Mount Wilson Observatory, Mount Wilson, CA 91023.]
McAlister, H. A. [Center for High Angular Resolution Astronomy, Department of Physics and Astronomy, Georgia State University, P.O. Box 3969, Atlanta, GA 30302-3969.]
Sturmann, J. [CHARA Array, Mount Wilson Observatory, Mount Wilson, CA 91023.]
Sturmann, L. [CHARA Array, Mount Wilson Observatory, Mount Wilson, CA 91023.]
Turner, N. H. [CHARA Array, Mount Wilson Observatory, Mount Wilson, CA 91023.]
1-Jul-2006
Astrophysical Journal
University of Chicago Press
645
664-675
Yes (verified by ORBi)
International
0004-637X
Chicago
IL
[en] Methods: Numerical ; Stars: Atmospheres ; stars: fundamental parameters (radii) ; stars: fundamental parameters (temperature) ; Stars: Individual: Name: Vega ; Stars: Rotation ; Techniques: Interferometric
[en] We have obtained high-precision interferometric measurements of Vega with the CHARA Array and FLUOR beam combiner in the K' band at projected baselines between 103 and 273 m. The measured visibility amplitudes beyond the first lobe are significantly weaker than expected for a slowly rotating star characterized by a single effective temperature and surface gravity. Our measurements, when compared to synthetic visibilities and synthetic spectrophotometry from a Roche-von Zeipel gravity-darkened model atmosphere, provide strong evidence for the model of Vega as a rapidly rotating star viewed very nearly pole-on. Our best-fitting model indicates that Vega is rotating at ~91% of its angular break-up rate with an equatorial velocity of 275 km s[SUP]-1[/SUP]. Together with the measured vsini, this velocity yields an inclination for the rotation axis of 5deg. For this model the pole-to-equator effective temperature difference is ~2250 K, a value much larger than previously derived from spectral line analyses. A polar effective temperature of 10,150 K is derived from a fit to ultraviolet and optical spectrophotometry. The synthetic and observed spectral energy distributions are in reasonable agreement longward of 140 nm, where they agree to 5% or better. Shortward of 140 nm, the model is up to 10 times brighter than observed. The model has a luminosity of ~37 L[SUB]solar[/SUB], a value 35% lower than Vega's apparent luminosity based on its bolometric flux and parallax, assuming a slowly rotating star. Our model predicts the spectral energy distribution of Vega as viewed from its equatorial plane, and it may be employed in radiative models for the surrounding debris disk.
Researchers
http://hdl.handle.net/2268/19318
10.1086/504149
http://adsabs.harvard.edu/abs/2006ApJ...645..664A
http://www.iop.org/EJ/abstract/0004-637X/645/1/664/ - Copyright The American Astronomical Society (AAS) and IOP Publishing Limited 2009
http://de.arxiv.org/abs/astro-ph/0603327 - Erratum at the following URL: http://www.iop.org/EJ/abstract/-link=9618020/0004-637X/651/1/617

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