Instrumentation for Global Time-Series Photometry

除了太阳以外，脉动的白矮星在通过实验手段探测恒星内部结构方面显示出最大的潜力。通过恒星光度的变化，在表面可以看到丰富多样的振动波，在这些恒星中被激发，在整个恒星内部相互干扰。干涉的模式可以用来推断每一波通过的物质的量，因此最终可以确定物质通过恒星的分布。这些原理类似于地球上地震学家几十年来使用的原理，现在第一次被应用于遥远的恒星。白矮星是最好的候选者，不仅因为它们表现出如此多的振动，而且因为它们的周期足够短，可以通过观察恒星的光变化来跟踪许多波动周期。这位首席调查员在他的大部分研究生涯中都在设计和建造光度测量仪器，以进行准确的光测量。在之前的NSF奖项中，PI和他的合作者发现，他们建造的三通道光度计原型(一个通道用于计划恒星，一个通道用于恒定的“标准”，另一个用于无恒星的“天空”)增加了天文学家在夜间实际收集数据的时间。新的奖项将允许PI建造这个原型的两个便携式复制品。这些仪器将由他的同事运送到世界各地的观测地点。作为“观测行动”的一部分，目标恒星将在地球自转时由每个观测者同时观测。在这次活动之后，这些数据将被合并，并产生连续几天长的串，这对于分析白矮星的内部性质是必要的。

With the possible exception of the Sun, pulsating white dwarfs show the greatest potential for probing the interior structures of stars by experimental means. A rich variety of vibrating waves, visible at the surface by their change in the star's luminosity, are excited in these stars that interfere with one another throughout the star's interior. The pattern of interferences can be used to infer the amount of material each wave travels through, and hence the distribution of material through the star can ultimately be determined. These principles, similar to those used for decades by seismologists on the Earth, are now being applied to distant stars for the first time. The white dwarf stars are the best candidates not only because they exhibit so many vibrations but because their periods are short enough that many wave cycles can be followed by observing the stars' light variations. The Principal Investigator has spent most of his research career designing and building photometric instrumentation to make accurate light measurements. In a previous NSF award, the PI and his collaborators found that a prototype three-channel photometer they had constructed (one channel for the program star, one for a constant "standard", and one for a starless "sky") increases the amount of time during a night that an astronomer can spent actually collecting data. The new award will permit the PI to construct two portable duplicates of this prototype. These instruments will be transported by his colleagues to observing sites around the world. As part of an "observing campaign", target stars will then be observed in tandem by each of these observers as the Earth rotates. Following this campaign the data will be combined and a continuous several day-long string produced that is necessary for the analysis of interior properties of white dwarf stars.