Radial Velocity Variations of K-Giants

该奖项是一个为期两年的试点研究的创新 仪器技术获得精确的径向速度 星 该技术是插入一个最近构建的容器 在McDonald的Coude光谱仪的光束中充满碘气体 天文台 这种气体会吸收星光， 从而提供一组校准线 散布在光谱中的恒星线中。 与此 创新，PI期望获得径向速度， 精确度为+-5米/秒（大约8英里/小时）。 然后他会得到一个时间 一系列光谱的几个明亮的红巨星和搜索 脉动在其中。 PI已经使用了相关的 一种仪器技术来验证1.8天周期的存在 在红巨星大角星。 如果大角星的这种脉动 是其他红巨星的典型特征，然后是一类新的变星 就会被发现 这些数据将用于各种 其他天体物理学目的，包括对流的研究 循环细胞和这些恒星表面的磁性“活动”。 或者是脉动，或者是磁场活动，或者是这两种现象， 可能是加热外层大气的原因 （“色球”）的红巨星。 色球，反过来， 被认为会导致质量损失，这会显著影响 这颗星星的演化史

This award is for a two-year pilot study of an innovative instrumental technique to obtain precise radial velocities of stars. The technique is to insert a recently constructed container filled with iodine gas in beam of a coude spectrometer at McDonald Observatory. This gas will absorb starlight at well known wavelengths, thereby providing a set of calibration lines interspersed with the stellar lines in the spectrum. With this innovation, the PI expects to obtain radial velocities to an accuracy of +-5 m/sec (roughly 8 mph). He will then obtain a time series of spectra for several bright red giant stars and search for pulsations in them. The PI has already used a related instrumental technique to verfify the existence of a 1.8-day period in the red giant Arcturus. If this pulsation in Arcturus is typical of other red giants, then a new class of variable stars will have been discovered. The data will be used for a variety of other astrophysical purposes, including the study of convective circulation cells and magnetic "activity" on these stars surfaces. Either pulsations, magnetic activity, or both of these phenomena, could be responsible for heating the outer atmospheres ("chromospheres") of red giants. Chromospheres, in turn, are thought to cause a mass loss, which can significantly affect the subsequent history of the star's evolution.