Discovery of nonradial instability strips for hot, evolved stars

Journal Article · Sun May 01 04:00:00 EDT 1983 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/184023· OSTI ID:5911407

Starrfield, S G; Cox, A N; Hodson, S W; Pesnell, W D

We have performed radial and nonradial, linear, nonadiabatic pulsation analyses of model stellar envelopes in the effective temperature range from 8 x 10/sup 4/ K to 1.5 x 10/sup 5/ K. These models have total masses of 0.6 M/sub sun/ and radii chosen so that they line up along a pre-white dwarf cooling curve computed by Schoenberner. We use three different interior compositions: (1) 100% carbon: (2) 50% /sup 12/C and 50% /sup 16/O (by mass); and (3) 10% /sup 12/C and 90% /sup 16/O (by mass). We find nonradial and radial instability strips for each composition caused by the partial ionization of carbon or oxygen or both. Our objective is to find the cause of the observed pulsations of PG 1159-035, a hot, evolved star with T/sub e/> or =10/sup 5/ K. While this star may be too hot to lie within any of our new instability strips, the closest agreement comes from models with significant amounts of /sup 16/O near the stellar surface. If correct, this result implies that helium burning in envolved stars produces much more /sup 16/O than heretofore believed.

• Research Organization: Theoretical Division, Los Alamos National Laboratory, NM
• OSTI ID: 5911407
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 268:1; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
HELIUM BURNING
INSTABILITY
IONIZATION
MATHEMATICAL MODELS
OSCILLATION MODES
PULSATIONS
STAR BURNING
STAR EVOLUTION
STAR MODELS
STARS
STELLAR ATMOSPHERES
VARIABLE STARS