Paper published in a book (Scientific congresses and symposiums)Interferometric Constraints on Gravity Darkening with Application to the Modeling of Spica A & B
Aufdenberg, J. P.; Ireland, M. J.; Mérand, A. et al.
2007 • In Hartkopf, W. I.; Guinan, E. F.; Harmanec, P. (Eds.) Binary Stars as Critical Tools & Tests in Contemporary Astrophysics
Copyright Cambridge University Press, http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1072100
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Abstract :
[en] In 2005 we obtained very precise interferometric measurements of the pole-on rapid rotator Vega (A0 V) with the longest baselines of the Center for High Angular Angular Resolution (CHARA) Array and the Fiber Linked Unit for Optical Recombination (FLUOR). For the analysis of these data, we developed a code for mapping sophisticated PHOENIX model atmospheres on to the surface of rotationally distorted stars described by a Roche-von Zeipel formalism. Given a setof input parameters for a star or binary pair, this code predicts the interferometric visibility, spectral energy distribution and high-resolution line spectrum expected for the system. For the gravity-darkened Vega, our model provides a very good match to the K-band interferometric data, a good match to the spectral energy distribution -- except below 160 nm -- and a rather poor match to weak lines in the high dispersion spectrum where the model appears overly gravity darkened. In 2006, we used the CHARA Array and FLUOR to obtain high precision measurements of the massive, non-eclipsing, double-line spectroscopic binary Spica, a 4-day period system where both components are gravity darkened rapid rotators. These data supplement recent data obtained with the Sydney University Stellar Interferometer. Our study follows the classic 1971 study by Herbison-Evans et al. who resolved Spica as a binary with the Narrabri Intensity Interferometer. We will report on our progress modelling the new interferometric and archival spectroscopic data, with the goal towards better constraining the apsidal constant.
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