Period changes of d Scuti stars and stellar evolution

Autor(en)

Michel Breger, Aleksiej Pamiatnych

Abstrakt

Period changes of d Scuti stars have been collected or redetermined from the available observations and are compared with values computed from evolutionary models with and without convective core overshooting. For the radial pulsators of Pop. I, the observations indicate (1/P) dP/dt values around 10-7 year-1 with equal distribution between period increases and decreases. The evolutionary models, on the other hand, predict that the vast majority should show increasing periods. This increase should be a factor of about ten times smaller than observed. For nonradial d Scuti pulsators of Pop. I, the discrepancies are even larger. The behavior suggests that for these relatively unevolved stars the rate of evolution cannot be deduced from the period changes. The period changes of most Pop. II d Scuti (SX Phe) stars are characterized by sudden jumps of the order of ?P/P ~ 10-6. However, at least one star, BL Cam, shows a large, continuous period increase. The variety of observed behavior also seems to exclude an evolutionary origin of the changes. Model calculations show that the evolutionary period changes of pre-MS d Scuti stars are a factor of 10 to 100 larger than those of MS stars. Detailed studies of selected pre-MS d Scuti stars are suggested.

Organisation(en)

Institut für Astrophysik

Journal

Astronomy & Astrophysics

Band

332

Seiten

958-968

Anzahl der Seiten

11

ISSN

0004-6361

Publikationsdatum

1998

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/d3a30e74-b897-4aa4-9567-642b0f5dee97