Lampens, P. ; Torres, K. ; Frémat, Y. ; Hensberge, H.

published in American Institute of Physics Conference Series, 1170, pp. 446-448 (2009)

Abstract: The fortunate combination of a pulsating star in a binary system, for which independent constraints on the system's geometry and on the physical properties of the components can be derived, represents a fantastic opportunity for progress in stellar evolution and pulsation modelling. We selected the detached, ``single-lined'' Hyades binary θ2 Tau comprising two mid-A type stars for a detailed spectroscopic investigation of old as well as of new high-resolution échelle spectra. Its brighter component is a well-known δ Scuti star which shows a complex pattern of pulsations. The secondary component is also located in the lower Cepheid instability strip and a potential δ Scuti star. Notwithstanding the heavily blended lines in the observed composite spectra caused by the fast rotation of the secondary component, which previously impeded an accurate determination of the mass ratio of this system, we obtained the component spectra and the components' radial velocities associated to a new spectroscopic orbit using a spectra disentangling algorithm. Combining both spectroscopy and long-baseline optical interferometry, we were able to derive the orbital parallax and the component masses with unprecedented accuracy. The future perspectives of this work are (i) a confrontation of stellar evolution models for the Hyades cluster (both stars are located in the turn-off region of the cluster) (ii) an accurate determination of the chemical composition of two Hyades members and (iii) a more reliable pulsation modelling for the pulsating component(s).

DOI: 10.1063/1.3246541
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