arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1409.2402astro-ph.SR
收藏

在NGC ~3766颗快速旋转的SPB星中发现了一类新的变率星吗？

Are the stars of a new class of variability detected in NGC~3766 fast rotating SPB stars?

S. J. A. J. Salmon, J. Montalbán, D. R. Reese, M. -A. Dupret, P. Eggenberger

备注：
6 pages, 2 figures, to appear in the proceedings of the IAU Symposium 307, New windows on massive stars: asteroseismology, interferometry, and spectropolarimetry
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

最近对NGC~3766星团的光度测量发现了一些具有意想不到的变化的恒星。它们位于赫罗图中理论上没有脉动的区域，介于盾牌座$δ$和缓慢脉动B星（SPB）不稳定区域之间。它们的变异周期在$\sim$ 0.1--0.7~d之间，超出了这些已知的突变体的预期范围。NCG~3766星团是已知的快速旋转恒星。自转可以显著地影响恒星的脉动特性，并通过重力暗化改变它们的视光度。因此，我们检查新的变星是否可以对应于快速旋转的SPB星。在传统近似的框架内，我们对SPB脉动模的不稳定性和可见性进行了分析。重力暗化对典型SPB模型的影响进行了研究。我们发现在SPB不稳定带的红边界处，由于科里奥利效应，优先激发出周期在0.2- 0.5d范围内的平行扇形（PS）模。当恒星位于赤道上时，这些模式看起来最好。对于这样的倾角，由于重力变暗，低质量的SPB模型会显得更暗，就好像它们位于$δ$ ~Scuti和SPB不稳定带之间。

英文摘要：

A recent photometric survey in the NGC~3766 cluster led to the detection of stars presenting an unexpected variability. They lie in a region of the Hertzsprung-Russell (HR) diagram where no pulsation are theoretically expected, in between the $δ$ Scuti and slowly pulsating B (SPB) star instability domains. Their variability periods, between $\sim$0.1--0.7~d, are outside the expected domains of these well-known pulsators. The NCG~3766 cluster is known to host fast rotating stars. Rotation can significantly affect the pulsation properties of stars and alter their apparent luminosity through gravity darkening. Therefore we inspect if the new variable stars could correspond to fast rotating SPB stars. We carry out instability and visibility analysis of SPB pulsation modes within the frame of the traditional approximation. The effects of gravity darkening on typical SPB models are next studied. We find that at the red border of the SPB instability strip, prograde sectoral (PS) modes are preferentially excited, with periods shifted in the 0.2--0.5~d range due to the Coriolis effect. These modes are best seen when the star is seen equator-on. For such inclinations, low-mass SPB models can appear fainter due to gravity darkening and as if they were located between the $δ$~Scuti and SPB instability strips.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑