A Linear Nonadiabatic Analysis of Radial Oscillations in Models for Beta Cephei Stars

Davey, William R.

doi:10.1086/151862

Cited by 15 publications

(7 citation statements)

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“…With M * = 14.2 ± 0.4 M⊙, R * = 7.9 ± 0.6 R⊙, and the theoretical value Q = 0.035 (Davey 1973;Stothers 1976), this yields P fun = 0.18 ± 0.02 d, very close to the true pulsation period P ∼ 0.21 d. If the actual pulsation period is used to calculate Q, we obtain Q = P fun √ ρ = 0.041 ± 0.003.…”

Section: Fig 8 Shows ξmentioning

confidence: 91%

The pulsating magnetosphere of the extremely slowly rotating magnetic β Cep star ξ1 CMa

Shultz

Wade

Rivinius

et al. 2017

Monthly Notices of the Royal Astronomical Society

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ξ1 CMa is a monoperiodically pulsating, magnetic β Cep star with magnetospheric X-ray emission which, uniquely amongst magnetic stars, is clearly modulated with the star's pulsation period. The rotational period P rot has yet to be identified, with multiple competing claims in the literature. We present an analysis of a large ESPaDOnS dataset with a 9-year baseline. The longitudinal magnetic field B z shows a significant annual variation, suggesting that P rot is at least on the order of decades. The possibility that the star's Hα emission originates around a classical Be companion star is explored and rejected based upon VLTI AMBER and PIONIER interferometry, indicating that the emission must instead originate in the star's magnetosphere and should therefore also be modulated with P rot . Period analysis of Hα EWs measured from ESPaDOnS and CORALIE spectra indicates P rot > 30 yr. All evidence thus supports that ξ 1 CMa is a very slowly rotating magnetic star hosting a dynamical magnetosphere. Hα also shows evidence for modulation with the pulsation period, a phenomenon which we show cannot be explained by variability of the underlying photospheric line profile, i.e. it may reflect changes in the quantity and distribution of magnetically confined plasma in the circumstellar environment. In comparison to other magnetic stars with similar stellar properties, ξ 1 CMa is by far the most slowly rotating magnetic B-type star, is the only slowly rotating B-type star with a magnetosphere detectable in Hα (and thus, the coolest star with an optically detectable dynamical magnetosphere), and is the only known early-type magnetic star with Hα emission modulated by both pulsation and rotation.

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Section: Fig 8 Shows ξmentioning

confidence: 91%

The pulsating magnetosphere of the extremely slowly rotating magnetic β Cep star ξ1 CMa

Shultz

Wade

Rivinius

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…However, regarding heat-driven pulsations, the matter of whether a given period P might be due to pressure or gravity modes can even be more quantitatively evaluated with the associated value of the pulsation constant Q = P (M/M )/(R/R ) 3 . The pulsation constant is of the order of 0.033 − 0.042 d for the radial fundamental mode (Davey 1973;Lesh & Aizenman 1974;Fitch 1981;Stankov & Handler 2005), such that any value above this is indicative of gravity modes, while values below this correspond to pressure modes. For a (45M , 36R ) star, Q 0.03P, meaning that heat-driven p modes are expected to have periods shorter than ∼1 d for such stars, whereas periods longer than ∼1 d are likely to be those of g modes.…”

Section: Origin Of the Light Variationsmentioning

confidence: 99%

A BRITE view on the massive O-type supergiant V973 Scorpii: hints towards internal gravity waves or sub-surface convection zones

Ramiaramanantsoa

Ratnasingam

Shenar

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Stochastically-triggered photospheric light variations reaching ∼40 mmag peak-tovalley amplitudes have been detected in the O8 Iaf supergiant V973 Scorpii as the outcome of two months of high-precision time-resolved photometric observations with the BRIght Target Explorer (BRITE) nanosatellites. The amplitude spectrum of the time series photometry exhibits a pronounced broad bump in the low-frequency regime ( 0.9 d −1 ) where several prominent frequencies are detected. A time-frequency analysis of the observations reveals typical mode lifetimes of the order of 5 − 10 days. The overall features of the observed brightness amplitude spectrum of V973 Sco match well with those extrapolated from two-dimensional hydrodynamical simulations of convectively-driven internal gravity waves randomly excited from deep in the convective cores of massive stars. An alternative or additional possible source of excitation from a subsurface convection zone needs to be explored in future theoretical investigations.

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“…The results for P and its mass dependence are in good agreement with the estimates of Eggleton and Percy (1973). The periods of the 15 My model are the same as those found by Davey (1973).…”

Section: -32 4-30 Logtementioning

confidence: 57%

Evolutionary Effects on Radial Pulsations of β–Cephei Stars

Jensen

1974

Publ. Astron. Soc. Aust.

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During recent years it has become rather clear that the β-Cephei variables are in a hydrogen-buring stage of their evolution. The 8 (β-Cephei variables which have been found in the Scorpio-Centaurus association highlights this. The 6 of these variables for which Glaspey (1971) provides (β, (u – b)0) photometry all fall at the tip of the sequence in the Hertzsprung-Russell diagram. This indicates that (β-Cephei stars are in the final stages of core hydrogen burning. This is in good agreement with the position of the β-Cephei strip of Watson (1972) in the H-R diagram.

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A Linear Nonadiabatic Analysis of Radial Oscillations in Models for Beta Cephei Stars

Cited by 15 publications

References 0 publications

The pulsating magnetosphere of the extremely slowly rotating magnetic β Cep star ξ1 CMa

The pulsating magnetosphere of the extremely slowly rotating magnetic β Cep star ξ1 CMa

A BRITE view on the massive O-type supergiant V973 Scorpii: hints towards internal gravity waves or sub-surface convection zones

Evolutionary Effects on Radial Pulsations of β–Cephei Stars

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