Volume 556, August 2013
|Number of page(s)||11|
|Section||Stellar structure and evolution|
|Published online||25 July 2013|
KIC 11285625: A double-lined spectroscopic binary with a γ Doradus pulsator discovered from Kepler space photometry ⋆,⋆⋆
1 Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200B, 3001 Leuven, Belgium
2 Department of Astrophysics, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
3 Department of Physics, Faculty of Science, University of Zagreb, Croatia
4 INAF – Osservatorio Astronomico di Roma via Frascati 33, 00040 Monteporzio C. (RM), Italy
5 Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK
6 Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK
7 Stellar Astrophysics Center, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
Received: 15 April 2013
Accepted: 30 May 2013
Aims. We present the first binary modelling results for the pulsating, eclipsing binary KIC 11285625 that was discovered by the Kepler mission. An automated method to disentangle the pulsation spectrum and the orbital variability in high quality light curves was developed and applied. The goal was to obtain accurate orbital and component properties in combination with essential information derived from spectroscopy.
Methods. A binary model for KIC 11285625 was obtained, using a combined analysis of high-quality space-based Kepler light curves and ground-based high-resolution HERMES echelle spectra. The binary model was used to separate the pulsation characteristics from the orbital variability in the Kepler light curve in an iterative way. We used an automated procedure based on the JKTEBOP binary modelling code to perform this task, and adapted codes for frequency analysis and prewhitening of periodic signals. Using a disentangling technique applied to the composite HERMES spectra, we obtained a higher signal-to-noise mean spectrum for both the primary and the secondary components. A model grid search method for fitting synthetic spectra was used for fundamental parameter determination for both components.
Results. Accurate orbital and component properties of KIC 11285625 were derived, and we have obtained the pulsation spectrum of the γ Dor pulsator in the system. Detailed analysis of the pulsation spectrum revealed amplitude modulation on a timescale of a hundred days, and strong indications of frequency splittings at both the orbital frequency and the rotational frequency derived from spectroscopy.
Key words: stars: oscillations / binaries: spectroscopic / techniques: photometric / stars: rotation / stars: fundamental parameters / binaries: eclipsing
Partly based on observations made with the Mercator Telescope, which is operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Based on observations obtained with the HERMES spectrograph, which is supported by the Fund for Scientific Research of Flanders (FWO), Belgium, the Research Council of K.U. Leuven, Belgium, the Fonds National Recherches Scientific (FNRS), Belgium, the Royal Observatory of Belgium, the Observatoire de Genève, Switzerland, and the Thüringer Landessternwarte Tautenburg, Germany.
Full Table 5 is available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/556/A56
© ESO, 2013
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