À Propos Strange Pulsations of Blue Massive Stars

Abstract

The properties of radial nonlinear pulsations of massive blue stars are computed with the MESA software instrument in its dynamical mode. Pulsational instabilities could be computationally detected and followed if the evolutionary timestep was reduced to a fraction of the unfolding pulsation period. Stellar variability was recovered in regions on the HR plane that have been studied before and that are known to host LBVs and relatives. Mode properties are analyzed on the full stellar-evolution models, which are not in thermal equilibrium. Despite persistent numerical shortcomings, it appears possible to compute strange-mode - like pulsations of massive blue stars with MESA.

Figures (12)

• Figure 1: Evolutionary tracks of massive stars with superimposed instability regions in red. Epochs of steadily pulsating model stars, which are analyzed in more detail are highlighted and labeled.
• Figure 2: The very steep growth of the oscillatory variation of the total kinetic energy (in erg/s) of the model star saturates after about $1000$ days the simulation -- that is, after about $30$ cycles.
• Figure 3: The bolometric light variability of the double-mode pulsating model star folded with the dominant periodicity of $38.9$ days.
• Figure 4: The photometric V-band lightcurve of case-A model star folded with the period of 1.79 days.
• Figure 5: Case-A pulsation velocity curve folded with the period of 1.79 days.