KIC 10080943: An eccentric binary system containing two pressure- and gravity-mode hybrid pulsators⋆,⋆⋆
1 Institute for Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
2 Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
3 Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006, Australia
4 Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
5 Department of Astronomy and Astrophysics, Villanova University, 800 E. Lancaster Avenue, Villanova, PA 19085, USA
6 Isaac Newton Group of Telescopes, Apartado de Correos 321, 38700 Santa Cruz de la Palma, Canary Islands, Spain
7 Dr. Karl Remeis-Observatory & ECAP, Astronomisches Inst., FAU Erlangen-Nuremberg, 96049 Bamberg, Germany
Received: 12 July 2015
Accepted: 23 August 2015
Context. γ Doradus and δ Scuti pulsators cover the transition region between low mass and massive main-sequence stars, and as such, are critical for testing stellar models. When they reside in binary systems, we can combine two independent methods to derive critical information, such as precise fundamental parameters to aid asteroseismic modelling. In the Kepler light curve of KIC 10080943, clear signatures of gravity- and pressure-mode pulsations have been found. Ground-based spectroscopy revealed this target to be a double-lined binary system.
Aims. We present the analysis of four years of Kepler photometry and high-resolution spectroscopy to derive observational constraints with which to evaluate theoretical predictions of the stellar structure and evolution for intermediate-mass stars.
Methods. We used the method of spectral disentangling to determine atmospheric parameters for both components and derive the orbital elements. With phoebe, we modelled the ellipsoidal variation and reflection signal of the binary in the light curve and used classical Fourier techniques to analyse the pulsation modes.
Results. We show that the eccentric binary system KIC 10080943 contains two hybrid pulsators with masses M1 = 2.0 ± 0.1 M⊙ and M2 = 1.9 ± 0.1 M⊙, with radii R1 = 2.9 ± 0.1 R⊙ and R2 = 2.1 ± 0.2 R⊙. We detect rotational splitting in the g and p modes for both stars and use them to determine a first rough estimate of the core-to-surface rotation rates for the two components, which will be improved by future detailed seismic modelling.
Key words: stars: variables:δScuti / binaries: spectroscopic / stars: individual: KIC 10080943 / stars: fundamental parameters
Based on the data gathered with NASA’s Discovery mission, Kepler, and with the HERMES spectrograph, installed at the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias and supported by the Fund for Scientific Research of Flanders (FWO), Belgium, the Research Council of KU Leuven, Belgium, the Fonds National de la Recherche Scientific (F.R.S.–FNRS), Belgium, the Royal Observatory of Belgium, the Observatoire de Genève, Switzerland, and the Thüringer Landessternwarte Tautenburg, Germany.
Appendix A is available in electronic form at http://www.aanda.org
© ESO, 2015