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Slowly pulsating B stars (SPB) and $\gamma$ Dor stars pulsate in high-order gravity (g-) modes. The frequencies of g-modes are sensitive to the detailed structure and evolution history of stars having convective cores. Receding convective…

Solar and Stellar Astrophysics · Physics 2015-12-09 Ehsan Moravveji

Stability properties are presented of dipole and quadrupole nonradial oscillation modes of model stars that experienced a late helium shell flash on their way to the white-dwarf cooling domain. The computed instability domains are compared…

Astrophysics · Physics 2009-11-11 A. Gautschy , L. G. Althaus , H. Saio

The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars. We present a first general characterization of the pulsational behaviour of A-F type stars as observed in the…

After a historical introduction, I present the current status of our understanding of the mechanism responsible for pulsation in Beta Cephei and SPB stars.

Astrophysics · Physics 2008-12-12 W. A. Dziembowski

The lifetime of solar-like stars, the envelope structure of more massive stars, and stellar acoustic frequencies largely depend on the radiative properties of the stellar plasma. Up to now, these complex quantities have been estimated only…

All stars in the Kepler field brighter than 12.5 magnitude have been classified according to variability type. A catalogue of {\delta} Scuti and {\gamma} Doradus stars is presented. The problem of low frequencies in {\delta} Sct stars,…

Solar and Stellar Astrophysics · Physics 2018-06-13 Luis A. Balona

The region in the HR-diagram where the main sequence intersects the classical instability strip hosts A- and F-type stars exhibiting a rich variety of physical phenomena, such as pulsations on various time scales and chemical peculiarities.…

Solar and Stellar Astrophysics · Physics 2009-01-22 S. Hekker , Y. Frémat , P. Lampens , P. De Cat

Several classes of stars (most notably O and B main-sequence stars, as well as accreting white dwarfs and neutron stars) rotate quite rapidly, at spin frequencies greater than the typical g-mode frequencies. We discuss how rapid rotation…

Astrophysics · Physics 2009-10-30 Greg Ushomirsky , Lars Bildsten

In this review I present an overview of our current understanding of the physical mechanisms that are responsible for the excitation of pulsations in stars with surface convection zones. These are typically cooler stars such as the Delta…

Solar and Stellar Astrophysics · Physics 2012-01-04 G. Houdek

Context: Several hundred candidate hybrid pulsators of type A-F have been identified from space-based observations. Their large number allows both statistical analyses and detailed investigations of individual stars. This offers the…

Pulsation in beta Cep and SPB stars are driven by the kappa mechanism which depends critically on the metallicity. It has therefore been suggested that beta Cep and SPB stars should be rare in the Magellanic Clouds which have lower…

Astrophysics · Physics 2009-11-13 C. Karoff , T. Arentoft , L. Glowienka , C. Coutures , T. B. Nielsen , G. Dogan , F. Grundahl , H. Kjeldsen

Asteroseismology, the study of stellar vibration, has met with great success, shedding light on stellar interior structure, rotation, and magnetism. Prominently known as $\delta$ Scutis, intermediate-mass main-sequence oscillators that…

Solar and Stellar Astrophysics · Physics 2024-10-01 Subrata Kumar Panda , Shravan Hanasoge , Siddharth Dhanpal , Vageesh D. C

The space-based Kepler mission provided four years of highly precise and almost uninterrupted photometry for hundreds of $\gamma$ Doradus stars and tens of SPB stars, finally allowing us to apply asteroseismology to these gravity mode…

Solar and Stellar Astrophysics · Physics 2018-10-17 S. Christophe , J. Ballot , R. -M. Ouazzani , V. Antoci , S. J. A. J. Salmon

The B-type pulsators known as \beta Cephei and Slowly Pulsating B (SPB) stars present pulsations driven by the \kappa mechanism, which operates thanks to an opacity bump due to the iron group elements. In low-metallicity environments such…

Solar and Stellar Astrophysics · Physics 2015-06-04 S. Salmon , J. Montalbán , T. Morel , A. Miglio , M-A. Dupret , A. Noels

We present interpretation of the oscillation spectrum of the early B-type star $\gamma$ Pegasi, in which both low order p/g and high-order g-modes are observed. Using amplitudes and phases of the photometric and radial velocity variations,…

Solar and Stellar Astrophysics · Physics 2015-06-15 Przemysław Walczak , Jadwiga Daszyńska-Daszkiewicz , Alexey A. Pamyatnykh , Tomasz Zdravkov

The beta Cephei stars and slowly pulsating B (SPB) stars are massive main sequence variables. The strength of their pulsational driving strongly depends on the opacity of iron-group elements. As many of those stars naturally occur in young…

Solar and Stellar Astrophysics · Physics 2015-05-27 G. Handler

We present an overview of pulsating stars in close binaries, focusing on the question what role the dupliticity plays in triggering and/or modifying stellar oscillations and on how it can help us to interpret the oscillatory behaviour of…

Astrophysics · Physics 2007-05-23 Conny Aerts , Petr Harmanec

I examine the stability of retrograde mixed modes in rotating B-type stars. These modes can be regarded as a hybrid between the Rossby modes that arise from conservation of vorticity, and the Poincare modes that are gravity waves modified…

Astrophysics · Physics 2009-11-13 R. H. D. Townsend

Classification of over 50000 TESS stars in sectors 1-18 has resulted in the detection of 766 pulsating main sequence B stars as well as over 5000 $\delta$ Scuti, 2300 $\gamma$ Doradus and 114 roAp candidates. It is found that a distinct…

Solar and Stellar Astrophysics · Physics 2020-03-18 Luis A Balona , Dogus Ozuyar

Stability of radial and nonradial oscillations of massive supergiants is discussed. The kappa-mechanism and strange-mode instability exciteoscillations having various periods in wide ranges of the upper part of the HR diagram. In addition,…

Solar and Stellar Astrophysics · Physics 2015-05-20 Hideyuki Saio