Volume 554, June 2013
|Number of page(s)||10|
|Published online||11 June 2013|
Spherically-symmetric model stellar atmospheres and limb darkening
I. Limb-darkening laws, gravity-darkening coefficients and angular diameter corrections for red giant stars ⋆
1 Department of Physics & AstronomyEast Tennessee State University, Box 70652, Johnson City, TN 37614, USA
2 Department of Chemical and Physical Sciences, University of Toronto Mississauga, ON L5L 1C6, Canada
3 Department of Astronomy & Astrophysics, University of Toronto, ON M55, 3H4, Canada
Received: 18 March 2013
Accepted: 30 April 2013
Model stellar atmospheres are fundamental tools for understanding stellar observations from interferometry, microlensing, eclipsing binaries and planetary transits. However, the calculations also include assumptions, such as the geometry of the model. We use intensity profiles computed for both plane-parallel and spherically symmetric model atmospheres to determine fitting coefficients in the BVRIHK, CoRot and Kepler wavebands for limb darkening using several different fitting laws, for gravity-darkening and for interferometric angular diameter corrections. Comparing predicted variables for each geometry, we find that the spherically symmetric model geometry leads to different predictions for surface gravities log g < 3. In particular, the most commonly used limb-darkening laws produce poor fits to the intensity profiles of spherically symmetric model atmospheres, which indicates the need for more sophisticated laws. Angular diameter corrections for spherically symmetric models range from 0.67 to 1, compared to the much smaller range from 0.95 to 1 for plane-parallel models.
Key words: stars: atmospheres / stars: late-type / binaries: eclipsing / stars: evolution / techniques: interferometric
Tables 2–17, and the model intensity profiles are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/554/A98
© ESO, 2013
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