Solar-like oscillations in the G8 V star<i>τ</i> Ceti

Abstract

We used HARPS to measure oscillations in the low-mass star τ Cet. Although the data were compromised by instrumental noise, we have been able to extract the main features of the oscillations. We found τ Cet to oscillate with an amplitude that is about half that of the Sun, and with a mode lifetime that is slightly shorter than solar. The large frequency separation is 169 μHz, and we have identified modes with degrees 0, 1, 2, and 3. We used the frequencies to estimate the mean density of the star to an accuracy of 0.45% which, combined with the interferometric radius, gives a mass of (1.6%).