MOST Detects g-Modes in the Late-Type be Star beta CMi (B8Ve)

Abstract

The Microvariability and Oscillations of stars (MOST) satellite has detected low-amplitude light variations ($\hat{I}”m\sim$1 mmag) in the Be star ${\hat{I}}^2$ CMi (B8Ve). The observations lasted 41 days and the variations have typical periods $\sim 0.3$ 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 ($\approx 3.5M_{\odot }$) 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.

17 pages, 6 figures; Astrophysical Journal part 1 in press