arXiv 2103.134102021-03-24astro-ph.SR

演化模型对类太阳恒星自转速率的统计拟合

Statistical Fitting of Evolution Models to Rotation Rates of Sun-Like Stars

Angela A. Breimann, Sean P. Matt, Tim Naylor

备注：: 18 pages, 10 figures. Accepted for publication in ApJ
DOI：: 10.3847/1538-4357/abf0a3

摘要：

本文首次将二维拟合统计量$τ^2$应用于周期质量平面上的恒星自转演化模型（0.1 ~ 1.3 $M_{\odot}$）。$τ^2$统计同时考虑所有聚类旋转数据以返回拟合优度，从而允许数据驱动的REM改进。我们构建数据集上斯科，昴宿星和Praesepe，我们调整我们的REM。我们使用一致确定的恒星质量（通过匹配$K_\textrm{s}$等时线的星等计算）和文献旋转周期。作为第一次演示的$τ^2$统计，我们发现最适合的陀螺年代学年龄的Praesepe，这是在良好的协议与文献。然后，我们系统地改变三个参数，这决定了我们的恒星风力矩法的Rossby数的饱和和不饱和制度的依赖性，以及两者之间的过渡的位置。通过最小化$τ^2$，我们找到每个参数的最佳拟合值。这些值在星团、质量测定和初始条件之间略有不同，突出了$τ^2$的精度及其限制REM、陀螺年代学和理解恒星物理学的潜力。我们得到的REM，实现了最好的拟合形式的一个破碎的幂律转矩，统计学上改进了以前的REM使用类似的配方，但仍然没有同时描述所观察到的旋转分布的最低质量，其中有慢和快的旋转器的Praesepe年龄，和形状的收敛序列更高的质量。因此，为了准确地描述数据，需要REM的进一步复杂性。

英文摘要：

We apply for the first time a two-dimensional fitting statistic, $τ^2$, to rotational evolution models (REMs) of stars (0.1 to 1.3 $M_{\odot}$) on the period-mass plane. The $τ^2$ statistic simultaneously considers all cluster rotation data to return a goodness of fit, allowing for data-driven improvement of REMs. We construct data sets for Upper Sco, the Pleiades and Praesepe, to which we tune our REMs. We use consistently determined stellar masses (calculated by matching $K_\textrm{s}$ magnitudes to isochrones) and literature rotation periods. As a first demonstration of the $τ^2$ statistic, we find the best-fitting gyrochronology age for Praesepe, which is in good agreement with the literature. We then systematically vary three parameters which determine the dependence of our stellar wind torque law on Rossby number in the saturated and unsaturated regimes, and the location of the transition between the two. By minimising $τ^2$, we find best-fit values for each parameter. These values vary slightly between clusters, mass determinations and initial conditions, highlighting the precision of $τ^2$ and its potential for constraining REMs, gyrochronology, and understanding of stellar physics. Our resulting REMs, which implement the best-possible fitting form of a broken power-law torque, are statistically improved on previous REMs using similar formulations, but still do not simultaneously describe the observed rotation distributions of the lowest masses, which have both slow and fast rotators by the Praesepe age, and the shape of the converged sequence for higher masses. Further complexity in the REMs is thus required to accurately describe the data.

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英文摘要：

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