Markus Hareter
Konkoly Observatory of the Hungarian Academy of Sciences

Abstract
Binary stars are the best targets to accurately determine important parameters, such as the masses and the radii of the components. The delta Scuti star HD 51844 was observed in the CoRoT LRa02 as a target for asteroseismology. The well sampled light curve shows clearly p mode pulsation and a recurring brightening event ("heartbeat") with a period of 33.5 days, but no eclipses. Four HARPS spectra taken late 2009 revealed at least two components, roughly equally bright and of the same spectral type. Dedicated spectroscopy earlier this year confirmed the binary nature, the orbit period from photometry, and that the "heartbeat" is caused by the periastron brightening of the system. The spectra indicate a system of evolved stars with nearly equal masses (q = 1.02), where one component shows significant line profile variations while the profiles of the slightly more massive component are constant. The search for regular patterns in the frequency distribution of delta Scuti stars is much more complicated than in the case of solar-type pulsators. Nevertheless, such patterns allow to find the large frequency separation for low order modes and therefore to constrain the mean density of the pulsating star.

2013 October 24, 13:30

IA/U.Porto
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