Context. The interpretation of stellar pulsations in terms of internal structure depends on the knowledge of the fundamental stellar parameters. Long-base interferometers permit us to determine very accurate stellar radii, which are independent constraints for stellar models that help us to locate the star in the HR diagram. Aims. Using a direct interferometric determination of the angular diameter and advanced three-dimensional (3D) modeling, we derive the radius of the CoRoT target HDâ€‰ 49933 and reduce the global stellar parameter space compatible with seismic data. Methods. The VEGA/CHARA spectro-interferometer is used to measure the angular diameter of the star. A 3D radiative hydrodynamical simulation of the surface is performed to compute the limb darkening and derive a reliable diameter from visibility curves. The other fundamental stellar parameters (mass, age, and Teff) are found by fitting the large and small p-mode frequency separations using a stellar evolution model that includes microscopic diffusion. Results. We obtain a limb-darkened angular diameter of θLD = 0.445 ± 0.012 mas. With the Hipparcos parallax, we obtain a radius of R = 1.42 ± 0.04 Rȯ. The corresponding stellar evolution model that fits both large and small frequency separations has a mass of 1.20 ± 0.08 M ȯ and an age of 2.7 Gy. The atmospheric parameters are T eff = 6640 ± 100 K, log g = 4.21 ± 0.14, and [Fe/H] =-0.38. © 2011 ESO.
Publication Source (Journal or Book title)
Astronomy and Astrophysics
Bigot, L., Mourard, D., Berio, P., Thévenin, F., Ligi, R., Tallon-Bosc, I., Chesneau, O., Delaa, O., Nardetto, N., Perraut, K., Stee, P., Boyajian, T., Morel, P., Pichon, B., Kervella, P., Schmider, F., McAlister, H., Ten Brummelaar, T., Ridgway, S., Sturmann, J., Sturmann, L., Turner, N., Farrington, C., & Goldfinger, P. (2011). The diameter of the CoRoT target HD 49933: Combining the 3D limb darkening, asteroseismology, and interferometry. Astronomy and Astrophysics, 534 https://doi.org/10.1051/0004-6361/201117349