Magnetic fields of low mass stars

日珥是恒星日冕中的冷凝结，是太阳上研究得很好的物体，但在恒星上研究得较少。这些特徴最早是在20世纪80年代由Collier-Cameron和罗宾逊在快速旋转的星星剑鱼座AB星上观测到的，并发现它们在半径比太阳大得多的情况下被迫共同旋转。这些特征的共同旋转表明它们被磁环顶部的强磁场所包含，使它们成为恒星磁场结构的绝佳标记。观测只能通过ZDI推断恒星表面的磁场强度，并且没有已知的方法将其外推到恒星日冕。一个能够将星星周围特定位置的日珥形成与特定磁场结构联系起来的模型，在提供有关日冕磁场的信息方面可能是非常宝贵的。这些恒星的磁场与日珥位置之间的关系意味着，利用这些日珥位置的观测数据和合适的模型，就有可能解开这些恒星相关磁场结构的一些信息。因此，了解这些特征的形成地点将使我们能够更好地了解恒星磁场，这对我们理解恒星的演化非常重要。这些特征的喷射可能对轨道行星的演化以及这些行星是否有可能孕育生命以及理解这些特征从“年轻太阳”中喷射出来产生压倒性的影响这个项目的目的是建立在以前的工作，其中一个模型是用来计算这些弹弓双折射的形成地点，在不同的磁场结构，在赤道平面内的圆柱形几何形状。将这一模型扩展到赤道平面之外，再加上一个将这些模拟的地层位置映射到观测结果（并再次返回）的模型，将使目前的模型更加现实和有价值。

Prominences, cool condensations in stellar coronae, are well-studied objects on the sun but less so on stars. These features were first observed on the rapidly rotating star, AB Doradus by Collier-Cameron and Robinson, in the 1980s and were found to be in forced co-rotation at radii considerably larger than would be possible on the sun. The co-rotation of these features signalled their containment by strong magnetic fields at the tops of magnetic loops, making them excellent markers for the stellar magnetic field structure. Observations can only infer, by ZDI, the magnetic field strengths at the stellar surface and there is no known way to extrapolate this up to the stellar corona. A model that can connect prominence formation at a given site around the star with a certain magnetic field structure could be invaluable in providing information on the coronal magnetic field.The relationship between the magnetic field of these stars and the prominence positions means that, with data from observations of these prominence positions and a suitable model, it would be possible to unravel some information about the associated magnetic field structure of these stars. Thus, understanding the formation sites of these features would allow us to better understand the stellar magnetic field, which is important for our understanding of stellar evolution.The ejection of these features can have overwhelming effects on the evolution of orbiting planets and the potential of these planets to harbour life and understanding the ejection of such features from "young suns" could give us insight into the environment in which the Earth evolved.This project aims to build upon previous work where a model was developed for calculating the formation sites of these slingshot prominences, in various magnetic field structures, within the equatorial plane for a cylindrical geometry. Expansion of this model out of the equatorial plane, alongside a model for mapping these modelled formation sites to observational results (and back again) would make the current model more realistic and valuable.