标题： 来自疏散星团的X射线 显示英文标题

标题： X-rays from Open Clusters

摘要： 综述了目前对共龄疏散星团中冷恒星的X射线观测现状。重点放在对类太阳恒星的ROSAT结果上，总结了可用的观测数据集，并概述了由于研究低质量恒星X射线活动演化而牢固确立的细节。 随后讨论了尚未解决的观测问题，包括“超饱和”起源以及一个星团的观测能否代表所有同龄星团的X射线特性。强调了高空间分辨率X射线成像在识别星团成员方面的作用，并探讨了AXAF和XMM未来发展的前景。 显示英文摘要

摘要： The present state of X-ray observations of cool stars in coeval open clusters is reviewed. Concentrating on ROSAT results for solar-type stars, the available observational dataset is summarized along with those details of the evolution of X-ray activity of low mass stars which have been firmly established as a result. Observational questions which are as yet unresolved are then addressed, including the origin of ``supersaturation'' and whether observations of one cluster can represent the X-ray properties of all clusters at the same age. The role of high spatial resolution X-ray imaging as a tool for identifying cluster members is highlighted and the prospects for future developments with AXAF and XMM are discussed.