MOST Detects g ‐Modes in the Late‐Type Be Star β Canis Minoris (B8 Ve)

Abstract

The Microvariability and Oscillations of Stars (MOST) satellite has detected low-amplitude light variations (Δm~1 mmag) in the Be star β CMi (B8 Ve). The observations lasted 41 days and the variations have typical periods ~0.3 days. We demonstrate that the dominant frequencies are consistent with prograde high-order g-modes of m=-1 excited by the Fe bump of opacity in an intermediate-mass (~3.5 Msolar) star with a nearly critical rotation period of 0.38 days. This is the first detection of nonradial g-mode pulsations in a Be star later than B6 leading to the possibility that pulsations are excited in all classical Be stars. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute of Aerospace Studies, and the University of British Columbia with the assistance of the University of Vienna.