MOST detects SPBe pulsations in HD 127756 & HD 217543: Asteroseismic rotation rates independent of vsini
arXiv:0805.1720 · doi:10.1086/590369
Abstract
The MOST (Microvariability and Oscillations of Stars) satellite has discovered SPBe (Slowly Pulsating Be) oscillations in the stars HD 127756 (B1/B2 Vne) and HD 217543 (B3 Vpe). For HD 127756, 30 significant frequencies are identified from 31 days of nearly continuous photometry; for HD 217543, up to 40 significant frequencies from 26 days of data. In both cases, the oscillations fall into three distinct frequency ranges, consistent with models of the stars. The variations are caused by nonradial g-modes (and possibly r-modes) distorted by rapid rotation and excited by the opacity mechanism near the iron opacity bump. A comparison of pulsation models and observed frequency groups yields a rotation frequency for each star, independently of vsini. The rotation rates of these stars, as well as those of the SPBe stars previously discovered by MOST, HD 163868 and CMi, are all close to their critical values.
36 pages, 16 figures, 3 tables, accepted for publication in ApJ
References in corpus (6)
- A heuristic derivation of the uncertainty of the frequency determination in time series data
- Instability strips of SPB and beta Cephei stars: the effect of the updated OP opacities and of the metal mixture
- MOST Detects g-Modes in the Late-Type be Star beta CMi (B8Ve)
- Excitation and visibility of slow modes in rotating B-type stars
- Non-radial oscillations of the rapidly rotating Be star HD 163868
- MOST Photometry of the roAp Star HD 134214