Takafumi Sonoi, Hideyuki Umeda
Very massive stars are thought to be formed in the early Universe because of
a lack of cooling process by heavy elements, and might have been responsible
for the later evolution of the Universe. We had an interest in vibrational
stability of their evolution and carried out the linear nonadiabatic analysis
of radial and nonradial oscillations for population III very massive
main-sequence stars with $500-3000M_{\sun}$. We found that only the radial
fundamental mode becomes unstable due to the $\varepsilon$-mechanism for these
stars. The instability appears just after the CNO cycle is activated and the
nuclear energy generation rate becomes large enough to stop the
pre--main-sequence contraction, and continues during the early stage of the
core hydrogen burning. Besides, we roughly estimated amount of mass loss due to
the instability to know its significance.
View original:
http://arxiv.org/abs/1201.0884
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