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

田纳西州立大学田纳西州立大学将建造一台专用光谱仪，用于机器人跟踪太阳等恒星色球活动的变化。太阳高层大气中有一个区域，叫做色球，它是由磁场形成并加热的。色球中热气体的发射量告诉我们太阳在其内部发电机中产生了多少磁场。磁场和由此产生的辐射在11年的周期内变化，但已经记录了更长的周期。太空观测表明，太阳的总亮度在这个11年的周期中会有一些变化；历史数据表明，在更长的周期中，太阳的总亮度可能会发生更大的变化。使用新光谱仪进行的观测将记录大约300颗恒星的磁周期，这些恒星被选择来近似过去、现在和不久的将来的太阳条件。结合已经在TSU望远镜上为这些恒星收集的精确光度测量，新的数据将定义磁场活动改变类太阳恒星光度的方式，并预测太阳本身的变化幅度。综合的光谱和光度学结果将最终确定像太阳这样的古老恒星是否具有周期性变化，以及这些古老的矮星通常具有什么样的磁周期，因此太阳本身有多典型。他们将确定这些恒星中磁场活动非常低的时间有多普遍，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可能如何影响地球上的生命发展。光谱仪的设计几乎没有移动部件，可以集成到现有的2米自动望远镜中。光谱仪将测量恒星近紫外线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进行机器人观测，将使我们有可能获得更多的每颗恒星的观测结果，并在未来更容易地维护该计划。追随这些恒星几十年应该是可能的。来自TSU的这些数据最终将使我们深入了解太阳总能量和磁场输出的变化水平和时间尺度。这对于理解太阳对我们的气候和经济的影响是至关重要的。TSU是一所小型的、历史悠久的黑人大学，该仪器的开发将通过让非裔美国学生参与开发和使用最先进的仪器来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.