The Steady Accretion Discs Irradiated by the Central Neutron Star

The vertical structure of steady accretion discs surrounding a neutron star is investigated with the effect of X-ray irradiation from the central part. Incident X-ray and thermal radiation are treated in two-colour Eddington\u27s approximation. The structure of discs is modified by the X-ray irradiation, but the thickness is not increased remarkably

Note on a Hydrodynamic Model of FG Sge

A hydrodynamic model of FG Sge, the central star of a planetary,nebula, has been reexamined by using the code with rezoning technique. The pulsation period P=29 days is obtained for the model with the parameters, M=1 M_⊙, L=3200 L_⊙ and T_=5500 K. Stellingwerf\u27s analytical expression is used for the opacities. The calculated amplitude of light variation is 0.45 mag. The growth rate of pulsation is not so great and no strong atmospheric shock waves are found

Derivation of the Modal Coupling Coefficients of a Classical Cepheid Model

We have derived the modal coupling coefficients of a model cepheid from the result of hydrodynamic calculations. It is found that the character of the model is marginal to change from a single-periodic behavior to a double-periodic one

On Linear Nonadiabatic Pulsations of Yellow Bright Stars

Procedures for calculating linear nonadiabatic pulsations are rediscussed. Pulsation properties of yellow bright stars are calculated by using Zalewski\u27s procedures. The usefulness of this procedure is indicated. The fundamental periods obtained in the present work are very close to previously published results

The Characteristic of the Large-amplitude Pulsation in a Model Yellow Supergiant Star

The large-amplitude pulsation of a model yellow supergiant star is investigated by using a hydrodynamic code. The parameters of the model were M=1M_⦿, L=3200L⦿ and T_=5300K. The recurrence of the generation of strong shock wave is obtained in every several pulsation periods. The abrupt decrease of the pulsation period has found after the formation of extended atmospheres above the photosphere. The outer boundary conditions for the linear non-adiabatic approximation derived by Castor fail to reproduce this period