The opacity mechanism in B-type stars – I. Unstable modes in β Cephei star models

Dziembowski, W. A.; Pamyatnykh, A. A.

doi:10.1093/mnras/262.1.204

Cited by 184 publications

(121 citation statements)

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“…This is well justified because the pulsational instability mechanism and theoretical oscillation spectra of B stars were already reviewed by Dziembowski & Pamyatnykh (1992), Gautsschy & Saio (1993), Dziembowski et al (1993), Moskalik (1995), Dupret (2001), and others. More recent investigations (e.g.…”

Section: Oscillation Spectra Of Early-type Starsmentioning

confidence: 84%

“…The properties of the basic eigenfunctions, kinetic energy distributions and work integrals for models of B stars were already discussed by Dziembowski & Pamyatnykh (1992), Dziembowski et al (1993), Pamyatnykh (1999), Dziembowski (2009), Dupret (2001, and others. The proper behavior of the Rosseland-mean opacity and eigenfunctions are necessary, but not sufficient conditions for the κ-mechanism to work.…”

Section: Seismic Modelsmentioning

confidence: 92%

“…These two kinds of modes are well separated in the frequency-domain for stellar models near the zero age main sequence (ZAMS). Nonradial modes may have also mixed character for evolved main sequence (MS) stars (Dziembowski & Pamyatnykh 1992;Balona & Dziembowski 1999). Those B stars with predominant variations in frequency domain characteristic of p-modes are called β Cephei-type stars, while those with variations in the frequency domain characteristic of g-modes are called SPBtype stars.…”

Section: Oscillation Spectra Of Early-type Starsmentioning

confidence: 99%

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Seismic models of O and B stars with Kurucz’s opacity data

Cugier

2014

A&A

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Aims. We investigated seismic models of O and B stars calculated with the new Kurucz opacities implemented in the Opacity Project (OP) and Rogers & Iglesias OPAL opacity tables (OPAL). Methods. We studied the problem using Dziembowski's computer codes for linear, nonadiabatic, and nonradial oscillations. We considered seismic models of main sequence (MS) stars for different chemical compositions of elements in the mass-range 9 ≤ M ≤ 70 M . Results. The new opacity bump at lg T ≈ 5.06 that occurs in Kurucz's data influences evolutionary tracks mainly for M ≥ 30 M and markedly changes the driving zone for pulsations of stars in the whole mass range studied. We obtained no unstable oscillation modes for models corresponding to the abundance parameter Z ≤ 0.013 and only unstable low-frequency g-modes for 0.013 < Z ≤ 0.021. Conclusions. The opacity bump at lg T ≈ 5.3 should be significantly larger than the opacity bump at lg T ≈ 5.06 to drive pulsations of B stars in low-degree p-modes. Models with an increased OPAL (or OP) opacity bump at lg T ≈ 5.3 by a factor of about 1.7 have sufficiently large driving zones to excite modes in the β Cephei frequency-domain for 0.003 ≤ Z ≤ 0.021. These values of Z are in a good agreement with those derived spectroscopically for stars in the Galaxy and Magellanic Clouds.

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Section: Oscillation Spectra Of Early-type Starsmentioning

confidence: 84%

Section: Seismic Modelsmentioning

confidence: 92%

Section: Oscillation Spectra Of Early-type Starsmentioning

confidence: 99%

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Seismic models of O and B stars with Kurucz’s opacity data

Cugier

2014

A&A

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“…Investigation of unstable modes can place constraints on the internal structure of massive stars (e.g. Aerts et al 2003;Thoul et al 2003;Dupret et al 2004;Pamyatnykh et al 2004) as well as the underlying excitation mechanisms (e.g; Moskalik & Dziembowski 1992;Dziembowski & Pamiatnykh 1993;Dziembowski & Pamyatnykh 2008). The discovery of solar-like oscillations is thus an opportunity to go a step further in the understanding of those stars that still challenge theory (Dziembowski 2007).…”

Section: Introductionmentioning

confidence: 99%

Solar-like oscillations in massive main-sequence stars

Belkacem¹,

Dupret²,

Noels³

2010

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Motivated by the detection of stochastically excited modes in the massive star V1449 Aql, which is already known to be a β Cephei star, we theoretically investigate the driving by turbulent convection. By using a full non-adiabatic computation of the damping rates, together with a computation of the energy injection rates, we provide an estimate of the amplitudes of modes excited by both the convective region induced by the iron opacity bump and the convective core. Despite the uncertainties in the dynamical properties of these convective regions, we demonstrate that both regions are able to efficiently excite p modes above the CoRoT observational threshold and the solar amplitudes. In addition, we emphasise the potential asteroseismic diagnostics provided by each convective region, which we hope will help us to identify the region responsible for solar-like oscillations, and to place constraints on this convective zone. A forthcoming work will be dedicated to an extended investigation of the likelihood of solar-like oscillations across the Hertzsprung-Russell diagram.

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“…In particular, the spectral lines of these elements are the major source of opacity in hot stars driving pulsations in j3 Cephei and SPB stars by the classical K-mechanism (Dziembowski & Pamyatnykh, 1993;Gautschy & Saio, 1993). Recently, Fitzpatrick & Massa (1999) demonstrated the usefulness of the low-resolution IUE observations in deriving the metal abundance parameter, [m/H], simultaneously with the effective temperature (T e ff), surface gravity (g), angular diameter (6) and interstellar reddening parameter (E(B -V)).…”

Section: Introductionmentioning

confidence: 99%