Stellar Atmospheric Stratification Measured by Millisecond Spectrophotometry of Lunar Occultations

当辐射能从恒星内部通过其表层扩散时，它与这些表层的组成气体——原子、离子和分子——相互作用，并产生大量的吸收和发射线。这些线条构成了一种特征，可以用于地面观测和分析，告诉我们很多关于恒星大气的温度、密度和组成结构的信息。对于冷巨星来说，这是一个特别丰富的研究领域，因为它们的光具有丰富的光谱线。首席研究员（PI）建议在月球掩星期间使用毫秒时间分辨率分光光度法观测凉爽明亮的巨星。目标是测量这些恒星的扩展大气中光谱特征形成的平均深度，以及围绕其中一些恒星的尘埃壳的内层。此外，PI将测量这些恒星的角直径，并得出角直径与吸收特征和恒星颜色的依赖关系。

As radiant energy diffuses from a star's interior through its surface layers, it interacts with the constituent gases --atoms, ions, and molecules -- in those surface layers and produces a host of absorption and emission lines. These lines constitute a signature that is accessible to terrestrial observation and analysis, telling us a great deal about the temperature, density, and composition structure of stellar atmospheres. This is a particularly rich field of study in the case of cool giant stars, for their light is characterized by an abundance of spectral lines. The Principal Investigator (PI) proposes to use millisecond time resolution spectrophotometry in the observation of cool, bright giant stars during lunar occultations. The goal is to measure the mean depths of the formation of spectral features in the extended atmospheres of these stars and in the inner layers of the dust shells surrounding some of them. Furthermore, the PI will measure the angular diameters of these stars and derive the dependence of angular diameter on absorption features and the stars' colors.