论文标题
Hyades群集的X射线视图：已更新
The X-ray view of the Hyades cluster: updated
论文作者
论文摘要
我们重新审视主要序列hyades成员的X射线特性以及X射线发射与恒星旋转之间的关系。作为Hyades成员的输入目录，我们合并了来自GAIA DR2数据（包括Hyades Core及其潮汐尾巴）的三个最新成员列表。我们搜索了Rosat All-Sky调查（RASS）的X射线检测以及Hyades成员的Rosat，Chandra和XMM-Newton的指数，并采用了Kepler K2任务和其他资源的轮换期。我们找到了1066个真正的主要序列hyades成员中281个X射线检测，并为未检测到的来源提供统计上限。 F-和G型星的检测部分最高（72％），而K-和M型矮人的检测率较低（22％）。检测到的成员的X射线照明范围从〜$ 2 \ 2 \ times10^{27} $，用于较晚的M型矮人到〜$ 2 \ $ 2 \ times10^{30} $ erg s $^s $^{ - 1} $用于活动二进制文件。核心和潮汐尾部中的成员正式不同的X射线光度分布函数，这可能是由于我们hyades Tails样品中较大的田间恒星所致。与以前的研究相比，由于使用的hyades成员列表的差异，我们的样本在X射线中略有淡淡，此外，我们将X射线光度分布扩展到了淡淡的发光度。 F-和G型星的X射线活性以$ f_x/f_bol = 10^{ - 5} $很好地定义，并增加到后来的光谱类型，达到了与光谱类型M3更晚成员的饱和极限。对于具有多个时期数据的104个hyades成员，X射线通量的变化不到X射线的差异不到三倍。发现了204个Hyades成员的旋转周期，其中约有一半在X射线中检测到。为Coeval Hyades成员得出的活性旋转连接具有与研究不同年龄的恒星所获得的属性非常相似。
We revisit the X-ray properties of the main-sequence Hyades members and the relation between X-ray emission and stellar rotation. As input catalog for Hyades members, we combined three recent membership lists derived from Gaia DR2 data including the Hyades core and its tidal tails. We searched for X-ray detections from the ROSAT all-sky survey (RASS) and pointings from ROSAT, Chandra, and XMM-Newton of the Hyades members and adopted rotation periods derived from Kepler's K2 mission and other resources. We find an X-ray detection for 281 of 1066 bona fide main-sequence Hyades members and provide statistical upper limits for the undetected sources. F- and G-type stars have the highest detection fraction (72 %), while K- and M-type dwarfs have lower detection rates (22 %). The X-ray luminosities of the detected members range from ~$2\times10^{27}$ for late M-type dwarfs to ~$2\times10^{30}$ erg s$^{-1}$ for active binaries. The X-ray luminosity distribution functions formally differ for the members in the core and tidal tails, which is likely caused by a larger fraction of field stars in our Hyades tails sample. Compared to previous studies, our sample is slightly fainter in X-rays due to differences in the used Hyades membership list, furthermore, we extend the X-ray luminosity distribution to fainter luminosities. The X-ray activity of F- and G-type stars is well defined at $F_X/F_bol=10^{-5}$ and increases to later spectral types reaching the saturation limit for members later than spectral type M3. The X-ray flux varies by less than a factor of three between epochs for the 104 Hyades members with multiple epoch data. Rotation periods are found for 204 Hyades members, with about half of them being detected in X-rays. The activity-rotation-relation derived for the coeval Hyades members has properties very similar to those obtained by other authors investigating stars of different ages.
