Stellar Oscillations in Planet Hosting K Giant Stars
Zusammenfassung der Projektergebnisse
Our investigation into the pulsations of planet hosting K giant stars has demonstrated that • RV variations due to oscillations is most likely an ubiquitous phenomenon in K giant stars. • The amplitude and frequency of the RV variations due to oscillations follow the scaling relationships proposed by Kjeldsen & Bedding (1995). • It is possible to derive the large frequency spacing of K giant stars using ground-based observations. These, however, require an inordinate number of measurements. • It is possible to estimate the stellar mass from the amplitude of the main pulsation mode (Vosc) and the luminosity of the star. For K giant stars with good Hipparcos parallaxes this results in a mean error in the stellar mass of about 15%. In the near future GAIA will provide better determinations of the stellar luminosity making it possible to get good estimates of all K giant stars from current Doppler surveys for planets. • There is generally good agreement between asteroseismic stellar masses and those derived from evolutionary tracks. Our confirmation of the scaling relationship between Vosc and L/M has important implications in planet searches around intermediate mass evolved stars. There are a number of programs searching for planets around K giant stars. These programs have to determine an accurate mass for the host star, Virtually all of these lack the telescope resources to adequately measure the oscillation spectrum of the star, but all these targets are bright and have good Hipparcos-measured parallaxes. Our work demonstrates that one can get a good estimate of the stellar mass simply from the velocity amplitude of the dominant pulsation mode without the need of detecting many oscillation modes. These can be used to check the mass derived from evolutionary tracks. Our work also shows that for the most part mass determinations from evolutionary tracks can be trusted, but can be refined with asteroseismic measurements.
Projektbezogene Publikationen (Auswahl)
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“Angular Diameters and Effective Temperatures of 25 K Giant Stars from the CHARA Array”, ApJ, 710, 1365, 2010
Baines, E.K., Döllinger, M.P., Cusano, F., Guenther, E.W., Hatzes, A.P., McAlister, H.A., ten Brummelaar, T.A.,Turner, N.H., Sturmann, J., Sturmann, L., Goldfinger, P.J., Farrington, C.D., Ridgway, S.T.
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“The Mass of the Planet-hosting Giant Star ß Geminorum Determined from its P-mode Oscillation Spectrum”, A&A, 543, 98, 2012
Hatzes, A.P., Zechmeister, M., Matthews, J., Kushnig, R., Walker. G.A.H., Döllinger, M., Guenther, D.B., Moffat, A.F., Rucinski, S.M., Sasselov, D., Weiss, W.W.
