Research Note: Solar-like oscillations in Hydri: Confirmation of a stellar origin for the excess power^*

¹ Observatoire de Genève, 1290 Sauverny, Switzerland
² School of Physics A28, University of Sydney, NSW 2006, Australia
³ Theoretical Astrophysics Center, University of Aarhus, 8000 Aarhus C, Denmark
⁴ Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Road NW, Washington, DC 20015-1305, USA
⁵ Anglo-Australian Observatory, PO Box 296, Epping, NSW 1710, Australia
⁶ Department of Astronomy, University of California, Berkeley, CA 94720, USA
⁷ Department of Physics and Astronomy, San Francisco, CA 94132, USA

Corresponding author: F. Carrier, Fabien.Carrier@obs.unige.ch

Received: 14 March 2001
Accepted: 10 August 2001

Abstract

The G2 subgiant β Hyi (HR 98) was observed with the Coralie fiber-fed echelle spectrograph on the 1.2-m Swiss telescope at La Silla in June 2000. The resulting 971 high-accuracy radial velocities exhibit an rms scatter of 2.72 m s^-1 and a mean noise level in the amplitude spectrum of 0.122 m s^-1. These measurements show significant excess in the power spectrum between 0.7-1.4 mHz with 0.40 m s^-1 peak amplitude. Fitting the asymptotic relation to the power spectrum gives a large splitting of 58 μHz which is in good agreement with theoretical expectations. Our data confirm the independent detection of solar-like oscillations in β Hyi announced by Bedding et al. ([CITE]) which used the Ucles echelle spectrograph on the 3.9-m Anglo-Australian Telescope. Two independent instruments and calibration methods obtained very similar power excesses thus leaving little doubts on the stellar origin of the detected signal.