Dynamics of Stellar Atmospheres

对星光的详细特征进行分析，以确定1)构成恒星大气层的气体的运动种类，2)恒星旋转的速度，3)恒星产生的磁场种类，以及4)恒星在太空中的运动速度。从这些测量中，我们了解了恒星中对流、脉动和旋转的物理过程，旋转如何与对流结合形成磁场，这些磁场如何在恒星表面造成黑斑，以及恒星逃逸的质量如何与恒星的磁场相互作用，起到刹车的作用，减缓其旋转。我的工作还包括对几十颗恒星进行多年的监测，以观察它们的变化，尤其是像太阳11年的磁周期这样的活动周期。由于地球上的生命严重依赖于我们的太阳，所以把太阳理解为一颗恒星并把它与其他恒星进行比较是很重要的。

Detailed features in starlight are analyzed to determine 1) the kinds of motions seen in the gases comprising the atmospheres of stars, 2) how rapidly stars spin, 3) the kinds of magnetic fields generated in the stars, and 4) how fast stars move in space. From these measurements, we learn about the physical processes of convection, pulsation, and rotation in stars, how rotation combines with convection to make magnetic fields, how those magnetic fields cause dark spots on the surfaces of stars, and how mass escaping from stars interacts with the magnetic field of the star, acting as a brake, to slow its rotation. My work also involves monitoring dozens of stars over many years to see their changes, especially activity cycles like the 11-year magnetic cycle shown by our sun. Since life on earth depends critically on our sun, it is important to understand the sun as a star and to compare it to other stars.