SMEI observations of previously unseen pulsation frequencies in Doradus

School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK e-mail: njt@bison.ph.bham.ac.uk

Received: 11 September 2008
Accepted: 22 September 2008

Abstract

Aims. As g-mode pulsators, gamma-Doradus-class stars may naïvely be expected to show a large number of modes. Taking advantage of the long photometric time-series generated by the solar mass ejection imager (SMEI) instrument, we have studied the star gamma Doradus to determine whether any other modes than the three already known are present at observable amplitude.

Methods. High-precision photometric data from SMEI taken between April 2003 and March 2006 were subjected to periodogram analysis with the PERIOD04 package.

Results. We confidently determine three additional frequencies at 1.39, 1.87, and 2.743 d^-1. These are above and beyond the known frequencies of 1.320, 1.364, and 1.47 d^-1.

Conclusions. Two of the new frequencies, at 1.39 and 1.87 d^-1, are speculated to be additional modes of oscillation, with the third frequency at 2.743^-1 a possible combination frequency.