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 ($\Delta m\sim$1 mmag) in the Be star $\beta$ 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

References in corpus (8)

• Be-star rotation: how close to critical?
• A Statistical Study of Threshold Rotation Rates for the Formation of Disks around Be Stars
• Most Detects G- and P-Modes in the B Supergiant HD 163899 (B2Ib/II)
• On the evolutionary status of Be stars. I. Field Be stars near the Sun
• Influence of the Coriolis force on the instability of slowly pulsating B stars
• Properties of the H-alpha-emitting Circumstellar Regions of Be Stars
• Differential rotation of the active G5V star Kappa1 Ceti: Photometry from the MOST satellite
• R modes of slowly pulsating B stars

Cited by in corpus (30)

• Ages for illustrative field stars using gyrochronology: viability, limitations and errors
• Classical Be Stars: Rapidly Rotating B Stars with Viscous Keplerian Decretion Disks
• Probing the interior physics of stars through asteroseismology
• Asteroseismology and Interferometry
• Kepler observations of variability in B-type stars
• CoRoT's view of newly discovered B-star pulsators: results for 358 candidate B pulsators from the initial run's exoplanet field data
• Beyond the Kepler/K2 bright limit: variability in the seven brightest members of the Pleiades
• Photometric Variability of the Be Star Population
• Gas Distribution, Kinematics, and Excitation Structure in the Disks around the Classical Be Stars Beta Canis Minoris and Zeta Tauri
• MOST detects SPBe pulsations in HD 127756 & HD 217543: Asteroseismic rotation rates independent of vsini
• Probing the properties of Be star discs with spectroastrometry and NLTE radiative transfer modelling: beta CMi
• Pulsations in the late-type Be star HD 50209 detected by CoRoT
• TESS observations of Be stars: a new interpretation
• New $\beta$ Cep pulsators discovered with K2 space photometry
• A photometric study of Be stars located in the seismology fields of COROT
• Short-term variability and mass loss in Be stars IV. Two groups of closely spaced, approximately equidistant frequencies in three decades of space photometry of $\nu$ Puppis (B7-8 IIIe)
• TESS observations of Be stars: general characteristics and the impulsive magnetic rotator model
• Amplitudes of low frequency modes in rotating B type stars
• Surveying the Bright Stars by Optical Interferometry III: A Magnitude-Limited Multiplicity Survey of Classical Be-Stars
• High-precision CoRoT space photometry and fundamental parameter determination of the B2.5V star HD 48977
• Stability of g-modes in rotating B-type stars
• Short-term variability and mass loss in Be stars VI. Frequency groups in $\gamma$ Cas detected by TESS
• Multitechnique testing of the viscous decretion disk model I. The stable and tenuous disk of the late-type Be star $\beta$ CMi
• Analysis of high-resolution FEROS spectroscopy for a sample of variable B-type stars assembled from TESS photometry
• Massive Star Asteroseismology in Action
• A new look into putative duplicity and pulsations of the Be star $\beta$ CMi
• Multiperiodicity in the newly discovered mid-late Be star V2104 Cygni
• Prospects for asteroseismology of rapidly rotating B-type stars
• Internal rapid rotation and its implications for stellar structure and pulsations
• Recent MOST space photometry