Radial and nonradial oscillations of 44 Tauri

Evolutionary stellar models of 44 Tauri, a multiperiodic delta Scuti star, have been developed theoretically and compared with earlier observational r eports. The models depict 44 Tau at the hydrogen-shell-burning stage, when it is in radiative equilibrium with a very thin surface convective layer. U sing the models, we performed calculations to obtain radial and nonradial a diabatic oscillation frequencies, and the equations were treated linearly. The results showed that the radial fundamental (6.899 cycles day(-1)) and f irst-overtone (8.961 cycles day(-1)) frequencies and the five nonradial mod es of low harmonic degree that had been determined theoretically were in ag reement with the observed values of previous authors to an accuracy of a fe w parts in 10(3). However, a difference emerged in the nonradial frequencie s, which we classified as g-modes of low harmonic degree, whereas the obser vational reports had classified them as p-modes. In addition, even though 4 4 Tau has a rotation v sin i = 6.8 km s(-1) (according to Solano and Fernle y), which we considered negligible, we analyzed the effect of rotation. Our findings revealed that rotation modulated the oscillation frequencies of t he nonrotating model on the order of 10(-2).