Auflösung von magnetischen Oberflächendetails bei vollkonvektiven Sternen mit Hilfe tomographischer Linieninversion

以前的演化恒星和单个主序恒星的多普勒图像显示了这两类天体和我们的太阳在磁活动类型上的有趣差异；极斑的存在和性质是发现的最显著的差异之一。随着8-10米级望远镜的出现，现在将多普勒成像技术推广到主序列非常凉爽的一端的时机似乎已经成熟。在那里，恒星被认为是完全对流的，因此不可能像太阳和类似的恒星那样，拥有一个很可能阻碍太阳发电机的过冲层。因此，人们可以预料到，与太阳和类似恒星上的磁场拓扑结构完全不同，因此表面温度分布和新的磁活动现象也会有本质上的不同。观察这些差异将有助于更好地理解太阳跃层对恒星发电机的作用，特别是对发电机理论的总体理解。

Previous Doppler images of evolved stars and of single pre-main-sequence stars reveal interesting differences in the types of magnetic activity seen in these two classes of objects and our Sun; the presence and nature of polar spots is one of the most striking differences found. With the advent of 8--10m-class telescopes, the time seems ripe now to extend the Doppler-imaging technique to thevery cool end of the main sequence. There, stars are thought tobe fully convective and therefore cannot possess an overshoot layerthat, as in the case of the Sun and similar stars, most likely harborsthe solar dynamo. Therefore, one could expect a fundamentally different magnetic-field topology than on the Sun and similar stars and thus a qualitatively different surface temperature distribution and new magnetic activity phenomena. Observing these differences would help to better understand the role of the solar tachocline for stellar dynamos in particular and dynamo theory in general.