High-precision Asteroseismology in a Slowly Pulsating B Star: HD 50230
High-precision Asteroseismology in a Slowly Pulsating B Star: HD 50230
复制标题
缓慢脉动 B 星的高精度星震学：HD 50230
DOI：
10.3847/1538-4357/ab2ad8
复制
发表时间：
2019
影响因子：
4.9
通讯作者：
Li Yan
中科院分区：
文献类型：
--
作者：
Wu Tao;Li Yan
缓慢脉动的B星HD 50230，实际上是一个混合的B型脉动器，已经被CoRoT观测了至少137天。从500多个频率的振动谱中提取的8个振型中，发现了几乎等距的周期间隔模式。然而，Szewczuk等人认为这很可能是偶然的。在本工作中，我们用χ2匹配方法对这八种模式进行了深入的分析。基于最佳拟合模型(MA模型)，我们发现它们可以很好地解释为连续偶极子序列(L，m)=(1，0)。在χ2极小化模型的基础上，我们发现，对于纯g模振荡，浮力半径Λ0可以用χ2匹配法精确测量。它代表了g模从恒星表面到中心的“传播时间”。其Λ为245.78±0.59μHz，测量精度为0.24%。此外，我们还发现HD 50230是一颗富金属星(Zinit=0.034-0.043)，质量为M=6.15-6.27M⊙。它仍处于中心氢Xc=0.298-0.316(或)的烧氢相，因此具有半径为Rcc=0.525-0.536 R⊙(或)的对流中心。为了更好地解释观测到的周期间隔模式的结构，在理论模型中应考虑对流中心超调(fov=0.0175-0.0200)和额外扩散混合()。
The slowly pulsating B star HD 50230, which is in fact a hybrid B-type pulsator, has been observed by CoRoT for at least 137 days. Nearly equidistant period spacing patterns are found among eight modes that are extracted from the oscillation spectrum with more than 500 frequencies. However, it is thought to be most likely accidental by Szewczuk et al. In the present work, we analyze the eight modes in depth with the χ2-matching method. Based on the best-fitting model (model MA), we find that they can be well explained as sequences of consecutive dipolar (l, m) = (1, 0). The period discrepancies between observations and the best-fitting model are within 100 s except for the outlier, which is up to 300 s. Based on the calculated χ2-minimization models, we find that, for pure g-mode oscillations, the buoyancy radius, Λ0, can be precisely measured with the χ2-matching method between observations and calculations. It represents the “propagation time” of the g-mode from the stellar surface to the center. It is of Λ0 = 245.78 ± 0.59 μHz with a precision of 0.24%. In addition, we also find that HD 50230 is a metal-rich (Zinit = 0.034–0.043) star with a mass of M = 6.15–6.27 M⊙. It is still located in the hydrogen-burning phase with central hydrogen of XC = 0.298–0.316 (or ); therefore, it has a convective core with a radius of Rcc = 0.525–0.536 R⊙ (or ). In order to interpret the structure of the observed period spacing pattern well, the convective core overshooting (fov = 0.0175–0.0200) and the extra diffusion mixing ( ) should be taken into account in theoretical models.