We present a study of the β Cephei instability strip based on a sample of 49 stars of this type. After deriving their effective temperatures and luminosities from their observed (B - V), (U - B) colors and parallaxes...We present a study of the β Cephei instability strip based on a sample of 49 stars of this type. After deriving their effective temperatures and luminosities from their observed (B - V), (U - B) colors and parallaxes we find their positions in the HR diagram to be mostly confined to the main sequence, and their masses to lie between 7 M⊙ and 30 M⊙ . Their distribution on the HR diagram matches well with our previous theoretical instability strip which has an upper bound in the luminosity and rather tight boundaries in the effective temperature.展开更多
We aim at investigating the effect of rotation up to the third order in the angular velocity of a star on the p and g modes, based on the formalism developed by Soufi et al. Our ultimate goal is the study of oscillati...We aim at investigating the effect of rotation up to the third order in the angular velocity of a star on the p and g modes, based on the formalism developed by Soufi et al. Our ultimate goal is the study of oscillations of β Cephei stars which are often rapidly rotating stars. Our results show that the third-order perturbation formalism presented by Soufi et al. should be corrected for some missing terms and some misprints in the equations. As a first step in our study of β Cephei stars, we quantify by numerical calculations the effect of rotation on the oscillation frequencies of a uniformly rotating zero-age main-sequence star with 12 M⊙. For an equatorial velocity of 100 km s^-1, it is found that the second- and third-order corrections for （l, m） = （2, 2）, for instance, are of the order of 0.01% of the frequency for radial order n = 6 and reaches up to 0.5% for n = 14.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘We present a study of the β Cephei instability strip based on a sample of 49 stars of this type. After deriving their effective temperatures and luminosities from their observed (B - V), (U - B) colors and parallaxes we find their positions in the HR diagram to be mostly confined to the main sequence, and their masses to lie between 7 M⊙ and 30 M⊙ . Their distribution on the HR diagram matches well with our previous theoretical instability strip which has an upper bound in the luminosity and rather tight boundaries in the effective temperature.
文摘We aim at investigating the effect of rotation up to the third order in the angular velocity of a star on the p and g modes, based on the formalism developed by Soufi et al. Our ultimate goal is the study of oscillations of β Cephei stars which are often rapidly rotating stars. Our results show that the third-order perturbation formalism presented by Soufi et al. should be corrected for some missing terms and some misprints in the equations. As a first step in our study of β Cephei stars, we quantify by numerical calculations the effect of rotation on the oscillation frequencies of a uniformly rotating zero-age main-sequence star with 12 M⊙. For an equatorial velocity of 100 km s^-1, it is found that the second- and third-order corrections for （l, m） = （2, 2）, for instance, are of the order of 0.01% of the frequency for radial order n = 6 and reaches up to 0.5% for n = 14.
