| |
 |
| Paper: |
Rapid Rotation and Excitation of g-modes in B Stars |
| Volume: |
135, A Half Century of Stellar Pulsation Interpretations: a Tribute to Arthur N. Cox |
| Page: |
104 |
| Authors: |
Ushomirsky, G.; Bildsten, L. |
| Abstract: |
Several classes of stars (most notably O and B main sequence stars, as well as white dwarfs and neutron stars in binary systems) rotate quite rapidly, i.e., at spin frequencies W greater than the typical g-mode frequencies w (but still small compared to the breakup frequency Wb@ (GM/R3)1/2. We discuss how rapid rotation modifies the frequencies and excitation mechanisms of g-mode oscillations. In particular, we show that the periods of g- modes in rapidly rotating stars scale as Pmode5 {Pspin P0}1/2, where P0 is the period in a nonrotating star. Excitation of pulsations by the k mechanism depends on the match between the period of the mode Pmode and the thermal timescale at the driving zone tth. By affecting the mode period, rapid rotation may destroy a match, thereby inhibiting pulsational instability. This means that g-mode instability strips may depend significantly on the stellar rotation rate, and stars that lie within the theoretical zero rotation instability strips may not actually pulsate by virtue of rapid rotation (conversely, stars outside the instability strips may be Rspun intoS pulsational instability by rapid rotation). We illustrate these ideas by considering pulsational stability of 53 Per stars as function of the rotation rate, since for these stars there are indications (Balona, L.A. 1994, MNRAS, 267, 1060; Balona, L.A. & Kohen, C. 1994, MNRAS, 267, 1071) that rapid rotation may play a role in inhibiting pulsations. |
|
|
|
|
|
