论文标题
X射线活性和M矮人中旋转的关系以及X射线光度的预测时间进化
Relation of X-ray activity and rotation in M dwarfs and predicted time-evolution of the X-ray luminosity
论文作者
论文摘要
我们提供了用XMM-Newton和Chandra观察到的14个M矮星的样本，为此，我们还从开普勒两轮（K2）Mission Light曲线中计算了旋转周期。我们从文献中编制了X射线和旋转数据，并均质化了所有数据集，以提供迄今为止X射线活性和旋转研究的最大均匀样品（302颗恒星）。然后，我们使用三个不同的质量垃圾箱在$ l _ {\ rm x} -p _ {\ rm rot} $之间适合$ l _ {\ rm x}之间的关系，以部分分离和完全对流的星星。我们在不饱和恒星的不饱和度方案中发现了一个陡峭的斜率，并且在所有群众的饱和度方案中，我们在饱和度方案中均为$ l _ {\ rm x} $级别。在$ l _ {\ rm x}/l _ {\ rm bol} -r _ {\ rm o} $空间中，我们发现了一个显着的双间隙，这可能与不连续的周期演变有关。然后，我们将$ p _ {\ rm rot} $的演变结合在一起，由角动量进化模型预测，我们在经验的$ l _ {\ rm x} -p _ {\ rm rot} $上提供了新的结果，以提供X射线LuminInitusisy年龄衰减的估算。我们将这种关系的预测与M星的实际X射线照明性进行比较，该恒星的实际X射线亮度从已知的年龄从100 MYR到数十亿年。我们发现预测的$ l _ {\ rm x} $与部分对流星的观察值之间的一致性非常好。但是，对于数十亿年的完全对流恒星，构建的$ l _ {\ rm x} - $年龄关系过高地预测了X射线光度，因为角动量进化模型预测了这些恒星的旋转时期。 Finally, we examine the effect of different parameterizations for the Rossby number ($R_{\rm O}$) on the shape of the activity-rotation relation in $L_{\rm x}/L_{\rm bol}-R_{\rm O}$ space, and we find that the slope in the unsaturated regime and the location of the break point of the dual power-law depend敏感地选择$ r _ {\ rm o} $。
We present a sample of 14 M dwarf stars observed with XMM-Newton and Chandra, for which we also computed rotational periods from Kepler Two-Wheel (K2) Mission light curves. We compiled X-ray and rotation data from the literature and homogenized all data sets to provide the largest uniform sample of M dwarfs (302 stars) for X-ray activity and rotation studies to date. We then fit the relation between $L_{\rm x} - P_{\rm rot}$ using three different mass bins to separate partially and fully convective stars. We found a steeper slope in the unsaturated regime for fully convective stars and a nonconstant $L_{\rm x}$ level in the saturated regime for all masses. In the $L_{\rm x}/L_{\rm bol}-R_{\rm O}$ space we discovered a remarkable double gap that might be related to a discontinuous period evolution. Then we combined the evolution of $P_{\rm rot}$ predicted by angular momentum evolution models with our new results on the empirical $L_{\rm x} - P_{\rm rot}$ relation to provide an estimate for the age decay of X-ray luminosity. We compare predictions of this relationship with the actual X-ray luminosities of M stars with known ages from 100 Myr to a few billion years. We find remarkably good agreement between the predicted $L_{\rm x}$ and the observed values for partially convective stars. However, for fully convective stars at ages of a few billion years, the constructed $L_{\rm x}-$age relation overpredicts the X-ray luminosity because the angular momentum evolution model underpredicts the rotation period of these stars. Finally, we examine the effect of different parameterizations for the Rossby number ($R_{\rm O}$) on the shape of the activity-rotation relation in $L_{\rm x}/L_{\rm bol}-R_{\rm O}$ space, and we find that the slope in the unsaturated regime and the location of the break point of the dual power-law depend sensitively on the choice of $R_{\rm O}$.
