Nonlinearity of Nonradial Modes in Evolved Stars
Abstract
We show that in evolved stars, even at relatively low surface amplitudes, nonradial modes become strongly nonlinear in the hydrogen shell source, where the Brunt-Väisälä frequency has its absolute maximum. The measure of nonlinearity is the product of horizontal displacement times the radial wavenumber, |\xi_H k_r|. It becomes large already in evolved δ-Scuti stars. This nonlinearity presents a major problem for interpretations of amplitude modulation in RR Lyrae stars in terms of nonradial mode excitation.
- Publication:
-
Astrophysics and Space Science
- Pub Date:
- 2003
- DOI:
- 10.48550/arXiv.astro-ph/0301504
- arXiv:
- arXiv:astro-ph/0301504
- Bibcode:
- 2003Ap&SS.284..273N
- Keywords:
-
- δ-Scuti stars;
- RR Lyrae stars;
- Astrophysics
- E-Print:
- 4 pages, 2 figures, to appear in "Asteroseismology Across the HR Diagram", Eds. Thompson M.J., Cunha M.S., Monteiro M.J.P.F.G., Kluwer, 2003