Development of a Dedicated Spectrograph for Robotically Measuring Chromospheric Emission of Stars like the Sun

田纳西州立大学将建造一个专用光谱仪，用于机器人跟踪像太阳这样的恒星色球活动的变化。太阳的上层大气中有一个叫做色球层的区域，它是由磁场形成和加热的。色球层中热气体的发射量告诉我们太阳内部发电机产生了多大的磁场。磁场和由此产生的辐射以11年为周期变化，但也有更长的周期记录。基于太空的观测表明，太阳的总亮度在这个11年的周期中有所变化；历史数据表明，在更长的周期内，它可能会发生更大的变化。用新的摄谱仪进行的观测将记录大约300颗恒星的磁周期，这些恒星被选中来近似太阳过去、现在和不久的将来的情况。结合TSU望远镜已经收集到的这些恒星的精确光度测量数据，新的数据将定义磁场活动改变类太阳恒星亮度的方式，并预测太阳本身应该变化多少。光谱学和光度学的综合结果将最终确定像太阳这样的老恒星是否具有周期性变化，以及这些老矮星通常具有什么样的磁周期，从而确定太阳本身有多典型。他们将确定这些恒星的磁场活动非常低的时期有多普遍，比如17世纪太阳的蒙德极小期。这些观测将进一步确定太阳磁场的历史如何影响地球上生命的发展。摄谱仪被设计成只有很少的活动部件，可以集成到现有的2米自动望远镜中。摄谱仪将测量恒星近紫外光谱中电离钙的色球发射，大约V=8等。在没有人类望远镜操作员的情况下，通过机器人进行观测，将有可能对每颗恒星进行更多的观测，并在未来更容易地维持该计划。跟踪这些恒星几十年应该是可能的。这些来自TSU的数据最终将使我们深入了解太阳总能量和磁场输出变化的水平和时间尺度。这对于了解太阳对我们的气候以及经济的影响程度至关重要。托国立是一所历史悠久的黑人小型大学，该仪器的开发将通过让非裔美国学生参与最先进仪器的开发和使用，促进科学和工程领域的种族多样性。

AST-0618404Joel EatonTennessee State UniversityTennessee State University will build a dedicated spectrograph for robotically tracking changes in the chromospheric activity of stars like the Sun. The Sun has a zone in its upper atmosphere, called the chromosphere, which is formed and heated by magnetic fields. The amount of emission of the hot gases in the chromosphere tells us how much magnetic field the Sun is generating in its internal dynamo. The magnetic field, and the resulting emission, varies on an 11-year cycle, but longer cycles have been documented. Space-based observations have shown that the Sun's total brightness changes somewhat over this 11-year cycle; historical data suggest it can change a great deal more over the longer cycle. The observations made with the new spectrograph will document magnetic cycles in about 300 stars chosen to approximate conditions of the Sun in the past, present, and near future. In combination with precise photometry already being collected on TSU telescopes for these same stars, the new data will define the way magnetic activity changes the luminosity of Sun-like stars and predict how much the Sun itself should vary. The combined spectroscopic and photometric results will ultimately determine whether old stars like the Sun are cyclically variable and just what kind of magnetic cycles these old dwarf stars typically have, hence how typical is the Sun itself. They will determine how prevalent times of very low magnetic activity, such as the Sun's Maunder minimum of the 17th century, are in these stars. These observations will further define how the history of solar magnetism may have affected development of life on the Earth.The spectrograph is designed with few moving parts and to be integrated into an existing 2-meter, automatic telescope. The spectrograph will measure chromospheric emission of ionized calcium in the near ultraviolet spectra of stars to about V=8 magnitude. Observing robotically, without human telescope operators, will make it possible to obtain more observations per star and to maintain the program more easily into the future. It should be possible to follow these stars for decades. These data from TSU will ultimately give us a deep understanding of the level and timescales of changes in the Sun's output of total energy and magnetic field. This is crucially important for understanding just how much the Sun affects our climate and thereby our economy. The development of this instrument at TSU ,a small, historically black university, will advance ethnic diversity in science and engineering by involving African-American students in development and use of state-of-the-art instrumentation.