论文标题
开放群集NGC 2527的多波长视图：发现活跃星星
A multi-wavelength view of the open cluster NGC 2527: Discovery of active stars
论文作者
论文摘要
恒星簇是对X射线发射恒星进行分类并研究X射线发射的理想平台，这是恒星年龄和活动的函数。我们通过结合XMM-UVOT-GAIA的数据，对开放型星团NGC2527进行了全面研究。恒星及其光度法的簇成员来自Gaia，并与XMM和UVOT探测交叉匹配。我们将NGC2527的年龄估计为〜630 Myr，用parsec等距为642 +/- 30 pc的距离为e（b-v）= 0.13 mag。我们检测到5个亚套件和5个带隙星，这无视单星的进化。我们使用Python代码估计53个单星和10个潜在二元星的温度，质量，半径和光度，该代码拟合了单个和复合库鲁兹光谱与宽带光谱能量分布。在12个X射线发射构件中，我们发现5个潜在的RS CVN型二进制组，其中2个是潜在的RGB恒星的FK COMAE类型，而5个是具有高冠状活性的主要序列（MS）恒星。具有强紫外发射的成员包括1 RGB恒星，几个MS星有过多的紫外线恒星。基于与其他群集的比较，我们初步建议RS CVN和接触二进制的X射线光度随着年龄的增长而增加，这表明与年轻的簇相比，较旧的簇中存在更多的活性二进制。这项研究表明，在年轻（约630 Myr）簇中可能存在W UMA和FK COMAE型星星。
Star clusters are ideal platforms for categorising X-ray emitting stars and to study X-ray emission as a function of stellar age and activity. We present a comprehensive study of an open star cluster, NGC2527, by combining data from XMM-UVOT-Gaia. Cluster membership of stars and their photometry are taken from Gaia and cross-matched with XMM and UVOT detections. We estimate the age of NGC2527 as ~630 Myr, reddening as E(B-V)=0.13 mag, and a distance of 642+/-30 pc using PARSEC isochrones. We detect 5 sub-subgiants and 5 bandgap stars, which defy single star evolution. We estimate the temperature, mass, radius, and luminosity of 53 single stars and 10 potential binary stars using a python code which fits single and composite Kurucz spectra to broad-band Spectral Energy Distribution. Among the 12 X-ray emitting members, we find 5 are potential RS CVn type binaries, 2 are potential FK Comae type of RGB stars, and 5 are main sequence (MS) stars with high coronal activity. Members with strong UV emission comprise of 1 RGB star, and several MS stars with UV excess suggestive of chromospheric activity. Based on comparison with other clusters, we tentatively suggest that X-ray luminosity of both RS CVn and contact binaries increases with age suggesting more active binaries are present in older clusters as compared to younger clusters. This study suggests the possible presence of W UMa and FK Comae type stars in younger (age~630 Myr) clusters.
