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Solar-like oscillators in Binary systems: a way to put tight constraints on stellar physics.
Paul Beck (CEA, Paris-Saclay), P. Gaulme (New Mexico State University, Department of Astronomy, USA), T. Kallinger (Institut fuer Astrophysik, Vienna University, Austria), A. Palacios (LUPM - Université de Montpellier), et al.
The growing number of binary stars with oscillating components from Kepler space photometry (Beck et al. 2014, Gaulme et al. 2014) or ground-based spectroscopy (Beck et al. 2015) provides a large sample of rewarding objects to study stellar physics. In this case study we discuss a detailed analysis of a particular binary system, nicknamed ‘Asterix & Obelix’, hosting two oscillating giant components. Besides mass and radius, we confront the rotational rates from seismology with the surface rotation. Judged from the period of spot modulation some systems have stellar rotation rates close to (nearly) the orbital period, such as this system, others do not show signs of synchronization at all. For a good understanding of the system, a detailed light curvemodel is discussed and compared to other well-studied systems. Such an analysis clearly benefits from the spectral disentangling of both stellar components from the time series of high-resolution spectroscopy, which enables us to constrain the mass ratio to about 1% as well as the individual stellar fundamental parameters and metallicities. In particular, confronting the so derived lithium abundance for both components with model predictions us to constraint the history of mixing and angular-momentum transport inside the stars. We also propose new ways how double-lined binaries can serve as a tool to calibrate the scaling relations by rewriting the relations with spectroscopic terms. We furthermore present a substantial extension to the dataset of known binary systems hosting solar-like oscillating components on the main sequence or the red-giant phase from photometry and spectroscopy.