Most Detects G- and P-Modes in the B Supergiant HD 163899 (B2Ib/II)

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dc.creatorSaio, H.
dc.creatorKuschnig, R.
dc.creatorGautschy, A.
dc.creatorCameron, C.
dc.creatorWalker, G. A. H.
dc.creatorMatthews, J. M.
dc.creatorGuenther, D. B.
dc.creatorMoffat, A. F. J.
dc.creatorRucinski, S. M.
dc.creatorSasselov, D.
dc.creatorWeiss, W. W.
dc.date2006-06-29
dc.date.accessioned2026-07-07T10:39:26Z
dc.date.available2026-07-07T10:39:26Z
dc.descriptionThe {\it Microvariability and Oscillations of Stars (MOST)} satellite observed the B supergiant HD 163899 (B2 Ib/II) for 37 days as a guide star and detected 48 frequencies $\la$ 2.8 c d$^{-1}$ with amplitudes of a few milli-magnitudes (mmag) and less. The frequency range embraces g- and p-mode pulsations. It was generally thought that no g-modes are excited in less luminous B supergiants because strong radiative damping is expected in the core. Our theoretical models, however, show that such g-modes are excited in massive post-main-sequence stars, in accordance with these observations. The nonradial pulsations excited in models between $20M_\odot$ at $\log T_{\rm eff} \approx 4.41$ and $15M_\odot$ at $\log T_{\rm eff} \approx 4.36$ are roughly consistent with the observed frequency range. Excitation by the Fe-bump in opacity is possible because g-modes can be partially reflected at a convective zone associated with the hydrogen-burning shell, which significantly reduces radiative damping in the core. The {\it MOST} light curve of HD 163899 shows that such a reflection of g-modes actually occurs, and reveals the existence of a previously unrecognized type of variable, slowly pulsating B supergiants (SPBsg) distinct from $α$ Cyg variables. Such g-modes have great potential for asteroseismology.
dc.description24 pages, 9 figures, Astrophysical Journal in press
dc.identifierhttps://arxiv.org/abs/astro-ph/0606712
dc.identifierhttp://arxiv.org/abs/astro-ph/0606712
dc.identifierAstrophys.J.650:1111-1118,2006
dc.identifierdoi:10.1086/507409
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/181028
dc.subjectAstrophysics
dc.titleMost Detects G- and P-Modes in the B Supergiant HD 163899 (B2Ib/II)
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