Asteroseismology and forced oscillations of HD 209295, the first member of two classes of pulsating star

Handler, G.; Balona, L. A.; Shobbrook, R. R.; Koen, C.; Bruch, A.; Romero-Colmenero, E.; Pamyatnykh, A. A.; Willems, B.; Eyer, L.; James, D. J.; Maas, T.; Crause, L. A.

Asteroseismology and forced oscillations of HD 209295, the first member of two classes of pulsating star

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Description

We report the discovery of both intermediate-order gravity mode and low-order pressure mode pulsation in the same star, HD 209295. It is therefore both a gamma Doradus and a delta Scuti star, which makes it the first confirmed member of two classes of pulsating star. This object is located in a close binary system with an unknown, but likely degenerate companion in an eccentric orbit, and some of the gamma Doradus pulsation frequencies are exact integer multiples of the orbital frequency. We suggest that these pulsations are tidally excited. HD 209295 may be the progenitor of an intermediate-mass X-Ray binary.
4 pages, 1 figure, to appear in the proceedings of IAU Colloquium 185 "Radial and Nonradial Pulsations as Probes of Stellar physics", C.Aerts, T.Bedding and J.Christensen-Dalsgaard, eds