The Detection of Multimodal Oscillations on α Ursae Majoris

Abstract

We have used the star camera on the Wide-Field Infrared Explorer satellite to observe the K0 III star alpha UMa, and we report the apparent detection of 10 oscillation modes. The lowest frequency mode is at 1.82 µHz, and it appears to be the fundamental mode. The mean spacing between the mode frequencies is 2.94 µHz, which implies that all detected modes are radial. The mode frequencies are consistent with the physical parameters of a K0 III star, if we assume that only radial modes are excited. Mode amplitudes are 100-400 µmag, which is consistent with the scaling relation of Kjeldsen & Bedding.