Astronomy and Astrophysics – Astronomy
Scientific paper
Aug 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008arep...52..645f&link_type=abstract
Astronomy Reports, Volume 52, Issue 8, pp.645-655
Astronomy and Astrophysics
Astronomy
97.10.Cv, 97.10.Me, 97.10.Sj, 97.30.Eh
Scientific paper
The evolution of Population I stars with initial masses 60 M &sun; ≤ M ZAMS ≤ 120 M &sun; is computed up to the Wolf-Rayet stage, when the central helium abundance decreases to Y c ≈ 0.05. Several models from evolutionary sequences in the core helium-burning stage were used as initial conditions when solving the equations of radiative hydrodynamics for self-exciting stellar radial pulsations. The low-density envelope surrounding the compact core during the core helium burning is unstable against radial oscillations in a wide range of effective temperatures extending to T eff ˜ 105 K. The e-folding time of the amplitude growth is comparable to the dynamical time scale of the star, and, when the instability ceases growing, the radial displacement of the outer layers is comparable to the stellar radius. Evolutionary changes of the stellar radius and luminosity are accompanied by a decrease in the amplitude of radial pulsations, but, at the effective temperature T eff ≈ 105 K, the stellar oscillations are still nonlinear, with a maximum expansion velocity of the outer layers of about one-third the local escape velocity. The period of the radial oscillations decreases from 9 hr to 4 min as stellar mass decreases from M = 28 M &sun; to M = 6 M &sun; in the course of evolution. The nonlinear oscillations lead to a substantial increase of the radii of the Lagrangian mass zones compared to their equilibrium radii throughout the instability region. The instability of Wolf-Rayet stars against radial oscillations is due to the action of the κ mechanism in the iron-group ionization zone, which has a temperature of T ˜ 2 × 105 K.
No associations
LandOfFree
Nonlinear radial pulsations of Wolf-Rayet stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Nonlinear radial pulsations of Wolf-Rayet stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nonlinear radial pulsations of Wolf-Rayet stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1173902