The discovery of stellar oscillations in the planet-hosting giant star β geminorum

We present the results of a long time series of precise stellar radial velocity measurements of the planet hosting K giant star beta Geminorum. A total of 20 hr of observations spanning three nights were obtained, and the radial velocity variations show the presence of solar-like stellar oscillations. Our period analysis yields six significant pulsation modes that have frequencies in the range of 30-150 mu Hz. The dominant mode is at a frequency of 86.9 mu Hz and has an amplitude of 5.3 m s(-1). These values are consistent with stellar oscillations for a giant star with a stellar mass of approximate to 2 M-circle dot. This stellar mass implies a companion minimum mass of 2.6 M-Jup. beta Gem is the first planet-hosting giant star in which multiperiodic stellar oscillations have been detected. The study of stellar oscillations in planet-hosting giant stars may provide an independent and more accurate determination of the stellar mass.