English

Characteristics of solar-like oscillations of secondary red clump stars

Solar and Stellar Astrophysics 2015-06-04 v1

Abstract

We calculated the populations of core-helium-burning (CHeB) stars and found that the secondary red clump (SRC) stars can form an SRC peak in the distributions of the frequency of maximum seismic amplitude (νmax\nu_{max}) and mean large-frequency separation (Δν\Delta\nu) of CHeB stars when metallicity ZZ \geq 0.02. The νmax\nu_{max} and Δν\Delta\nu of CHeB stars are dependent not only on He core mass but on H-shell burning. The SRC peak is composed of the CHeB stars with mass roughly between the critical mass M_{Hef} and M_{Hef}+0.2 while He core mass is between about 0.33 and 0.36 M_{sun}. The location of the SRC peak can be affected by the mixing-length parameter α\alpha, metallicity ZZ, and overshooting parameter δov\delta_{ov}. A decrease in α\alpha or increase in ZZ or δov\delta_{ov} leads to a movement of the SRC peak towards a lower frequency. However, the change in ZZ and α\alpha only slightly affects the value of M_{Hef} but the variation in δov\delta_{ov} can significantly affects the value of M_{Hef}. Thus the SRC peak might aid in determining the value of M_{Hef} and calibrating δov\delta_{ov}. In addition, the effects of convective acceleration of SRC stars and the νmax\nu_{max} of `semi-degenerate' stars decreasing with mass result in the appearance of a shoulder between about 40 and 50 μ\muhz in the \dnu{} distribution. However, the convective acceleration of stars with M < M_{Hef} leads to the deficit in the νmax\nu_{max} distribution between about 9 and 20 μ\muhz{}. Moreover, the value of the parameter bb of the relation between νmax\nu_{max} and Δν\Delta\nu for the populations with M > M_{Hef} is obviously larger than that for the populations with M<M < \dmhef{}.

Keywords

Cite

@article{arxiv.1202.2017,
  title  = {Characteristics of solar-like oscillations of secondary red clump stars},
  author = {Wuming Yang and Xiangcun Meng and Shaolan Bi and Zhijia Tian and Kang Liu and Tanda Li and Zhongmu Li},
  journal= {arXiv preprint arXiv:1202.2017},
  year   = {2015}
}

Comments

10 pages, 15 figures. Accepted for publication in MNRAS