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We propose to continue our XMM-Newton monitoring of the young solar analog epsilon Eri. So far only one X-ray cycle has been found on a star resembling the young Sun comma iota Hor openPar600Myr comma SpT G0VclosePar. Its X-ray cycle is remarkably one of the shortest dynamo cycles known to date openPar1.6 yrsclosePar comma the only X-ray cycle identified so far on a star with high chromospheric activity level. Our target comma epsilon Eri resembles iota Hor openParyoung age comma short calcium cycle comma high activityclosePar comma and our XMM-Newton measurements since AO14 suggest X-ray variability correlated with the known 3-yr Ca II cycle comma possibly with an anticipated rise phase during the last cycle. We ask for two snapshots in AO18 openPar2 x 5 ksecclosePar to be combined with our previous data and the continued Ca II monitoring of the star.

我们提议继续利用XMM-Newton卫星对年轻太阳类似星epsilon Eri进行监测。迄今为止，仅在一颗与年轻太阳相似的恒星——iota Hor（年龄6亿年，光谱型G0V）上发现过一个X射线活动周。该恒星的X射线活动周是目前已知最短的发电机循环之一（1.6年），也是迄今为止在高色球活动水平恒星上发现的唯一X射线活动周。我们的目标恒星epsilon Eri与iota Hor具有相似特征（年轻年龄、短钙活动周、高活动水平），且我们自AO14以来的XMM-Newton观测数据表明，其X射线变率与已知的3年Ca II活动周相关，在上一个活动周中可能存在预期的上升阶段。我们申请在AO18期间进行两次快照观测（每次5千秒，共两次），并将其与我们之前的数据及该恒星持续的Ca II监测数据相结合。