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Interferometric Gravity Darkening Observations of Vega with the CHARA Array
Aufdenberg, J. P.; Merand, A.; Coudé du Foresto, Vincent et al.
2006In Coudé du Foresto, V; Rouan, D; Rousset, G (Eds.) Visions for Infrared Astronomy
 

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Abstract :
[en] We have obtained high-precision interferometric measurements of the A0 V standard star Vega with the Center for High Angular Resolution Astronomy (CHARA) Array and the Fiber Linked Unit for Optical Recombination (FLUOR) beam combiner in the K' band at projected baselines between 103 m and 273 m. The measured squared visibility amplitudes beyond the first lobe are significantly weaker than expected for a slowly rotating star and provide strong evidence for the model of Vega as a rapidly rotating star viewed very nearly pole on. We have constructed a Roche-von Zeipel gravity-darkened model atmosphere which is in generally good agreement with both our interferometric data and archival spectrophotometry. Our model indicates Vega is rotating at Ë 92% of its angular break-up rate with an equatorial velocity of Ë 275 km s[SUP]-1[/SUP]. We find a polar effective temperature of Ë 10150 K and a pole-to-equator effective temperature difference of Ë 2500 K, much larger than the Ë 300 K derived by Gulliver, Hill, and Adelman. Our model suggests that Vega's cool equatorial atmosphere may have significant convective flux and predicts a significantly cooler spectral energy distribution for Vega as seen by its surrounding debris disk. This work was performed in part under contract with the Jet Propulsion Laboratory (JPL) funded by NASA through the Michelson Fellowship Program. JPL is managed for NASA by the California Institute of Technology. The CHARA Array is operated by the Center for High Angular Resolution Astronomy with support from Georgia State University and the National Science Foundation, the Keck Foundation and the Packard Foundation.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Aufdenberg, J. P.;  NOAO
Merand, A.;  LEISA
Coudé du Foresto, Vincent;  LEISA
Absil, Olivier  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Di Folco, E.;  LEISA
Kervella, P.;  LEISA
Ridgway, S. T.;  NOAO/NASA
Sturmann, J.;  CHARA Array
Sturmann, L.;  CHARA Array
ten Brummelaar, T. A.;  CHARA Array
Turner, N. H.;  CHARA Array
Berger, D. H.;  CHARA Array
McAlister, H. A.;  Georgia State University
More authors (3 more) Less
Language :
English
Title :
Interferometric Gravity Darkening Observations of Vega with the CHARA Array
Publication date :
March 2006
Event name :
Visions for Infrared Astronomy
Event organizer :
Rouan D. & Ridgway S.
Event place :
Paris, France
Event date :
du 20 au 22 mars 2006
Audience :
International
Main work title :
Visions for Infrared Astronomy
Editor :
Coudé du Foresto, V
Rouan, D
Rousset, G
Publisher :
Lavoisier
Collection name :
Instrumentation, Mesure, Métrologie vol 6/1-4
Pages :
305-308
Available on ORBi :
since 21 October 2014

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