Evidence for global oscillations in the K2 dwarf epsilon Eridani

Evidence of global p-mode oscillations in the K2 V star Epsilon Eridani, based on observed time variations in the Ca II H and K emission lines, is presented. Power spectra of time series of Ca II intensity measures reveal a number of peaks spaced at about 86 and 172 micro-Hz. The 172 micro-Hz spacing is significantly larger than the corresponding spacing observed for solar p-mode oscillations but is in excellent agreement with predictions for a star of the known radius of Epsilon Eri. The amplitude of the oscillations seen in the H and K flux of this chromospherically active star is much larger than in the sun. Peak power in the H and K fluctuations occurs at periods near 10 minutes, in contrast to predictions of peak oscillation amplitude near four minutes for a K2 dwarf.