Vibrational instability of Population III very massive main-sequence stars due to the inline image-mechanism

Authors

  • Takafumi Sonoi,

    Corresponding author
    1. Department of Astronomy, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
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  • Hideyuki Umeda

    1. Department of Astronomy, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
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E-mail: sonoi@astron.s.u-tokyo.ac.jp

ABSTRACT

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 the vibrational stability of their evolution and have carried out a linear non-adiabatic analysis of radial and non-radial oscillations for Population III very massive main-sequence stars with inline image. We found that only the radial fundamental mode becomes unstable due to the inline image-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 core hydrogen burning. Also, we have roughly estimated the amount of mass loss due to the instability to evaluate its significance.

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