标题： eROSITA和TESS对超活跃恒星AB Doradus的同时观测 显示英文标题

标题： Simultaneous eROSITA and TESS observations of the ultra-active star AB~Doradus

摘要： 我们展示了通过俄罗斯-德国 Spectrum-Roentgen-Gamma（SRG）任务的eROSITA仪器在X射线波段以及通过凌日系外行星巡天卫星（TESS）在光学波段对超活跃星AB Doradus的同步多波长观测结果。由于AB Dor位于南黄极附近的有利位置，这些任务对其进行了几乎长达20天的同时观测。利用迄今为止获得的数据，我们研究了AB Dor X射线流量的长期演化及其与恒星表面黑子活动的相关性。在eROSITA巡天观测的1.5年期间，AB Dor的“宁静”X射线流量没有变化，并且似乎与其由TESS观测到的光球面调制无关。在eROSITA和TESS的同步观测期间，观察到了一次总能量释放至少为4 $\times$ 10$^{36}$ erg的巨大光学耀斑事件，这是在AB Dor上观测到的最大耀斑。我们表明，该耀斑的总X射线输出远小于此，并讨论了这是否可能是晚型恒星耀斑的一个普遍特征。 显示英文摘要

摘要： We present simultaneous multiwavelength observations of the ultra-active star AB~Doradus obtained in the X-ray range with the eROSITA instrument on board the Russian--German Spectrum-Roentgen-Gamma mission (SRG), and in the optical range obtained with the Transiting Exoplanet Survey Satellite (TESS). Thanks to its fortuitous location in the vicinity of the southern ecliptic pole, AB~Dor was observed by these missions simultaneously for almost 20 days. With the hitherto obtained data we study the long-term evolution of the X-ray flux from AB~Dor and the relation between this observable and the photospheric activity of its spots. Over the 1.5 years of eROSITA survey observations, the "quiescent" X-ray flux of AB~Dor has not changed, and furthermore it appears unrelated to the photospheric modulations observed by TESS. During the simultaneous eROSITA and TESS coverage, an extremely large flare event with a total energy release of at least 4 $\times$ 10$^{36}$ erg in the optical was observed, the largest ever seen on AB~Dor. We show that the total X-ray output of this flare was far smaller than this, and discuss whether this maybe a general feature of flares on late-type stars.