Stellar Oscillations in Planet Hosting K Giant Stars

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This project will study stellar oscillations in planet hosting K giant star using precise stellar radial velocity measurements. These will be used to determine basic stellar parameters, in particular, the stellar mass. Extrasolar planets have been discovered around over 20 giant stars. These discoveries are important because the host stars have masses in the range of 1.1 - 2.5 Mʘ, signficantty higher than the masses of most planet hosting stars. Radial velocity surveys, which have discovered most of the known extrasolar planets, are ill-suited for planet searches around main sequence stars of this stellar mass because of the paucity of stellar lines and high stellar rotation rates. However, the determination of the stellar mass of giant stars is difficult because the evolutionary tracks of main sequence stars covering a wide range of masses all converge on the giant branch of the color magnitude diagram. Using the pulsation modes detected by our study we will derive accurate masses for a large sample of giant stars. Work with collaborators will use interferometric measurements to get accurate stellar radii for our program stars. The combined measurements of the stellar radii and masses for the program stars can ultimately be used to calibrate stellar evolutionary isochrones so that in future these can be used to determine accurate masses of planet hosting giant stars.