SunRISE Proposal: Precision Solar Disk Photometry--A Tool for Understanding Changes in the Sun's Luminosity

这一提议将继续目前正在进行的努力，以精确测量太阳表面的大范围亮度变化在整个太阳盘。在大熊太阳天文台建造了一种独特的专门仪器来进行这些测量，并获得了初步数据。利用一系列精确的光度测量数据，PI将进行一系列的调查：1)PI将把测量到的与纬度和时间相关的亮度变化与与时间相关的太阳常数测量结果进行比较。从光度计获得的更完整的空间信息将用于更好地理解短期和长期太阳光度变化的物理机制。例如，测量的平均纬度和>依赖的亮度结构（这里>是通常的日心角），与测量的光斑对比函数一起，可以直接测量光斑对太阳光度变化的贡献。此外，如果太阳的光度变化被确定（使用我们的光度数据）局限于活动纬度，那么精确的地面测量，如这里提出的，可以成为空间太阳常数测量的极好替代品，当后者不可用时。2) PI将更好地测量极赤道温差，并努力将周期相关的磁信号与可能与时间无关的微分旋转信号分离开来。这样的测量将限制太阳微分旋转的模型。3) PI将精确测量太阳极附近的亮度变化，以便更好地了解极磁场和极光斑。迄今为止，对太阳的大尺度亮度结构进行精确测量是一个很大程度上未被探索的研究领域。这些测量数据对理解和监测太阳的光度变化有很大的帮助。＃

This proposal will continue an ongoing effort to precisely measure large-scale solar surface brightness variations across the solar disk. A unique and specialized instrument to make these measurements has been constructed at Big Bear Solar Observatory, and preliminary data have been acquired. With a timeseries of precision photometric data, the PI will conduct a number of investigations: 1) The PI will compare measured latitude- and time-dependent brightness variations with time-dependent solar constant measurements. The more complete spatial information gotten from the photometer will be used to better understand the physical mechanisms responsible for short- and long-term solar luminosity variations. For example, measured average latitude- and >-dependent brightness structure (here > is the usual heliocentric angle), together with the measured facular contrast function, can be used to directly measure the contribution of faculae to solar luminosity changes. Further, if the Sun's luminosity variations are determined (using our photometric data) to be confined to the active latitudes, then precision ground-based measurements such as those proposed here could make an excellent substitute for space- based solar constant measurements, when the latter are unavailable. 2) The PI will make a better measurement of the pole-equator temperature difference, making some effort to separate the cycle- dependent magnetic signals from the presumably time-independent) differential rotation signal. Such a measurement will constrain models of the Sun's differential rotation. 3) The PI will accurately measure brightness variations near the solar pole, in order to get a better understanding of the polar magnetic fields and polar faculae. Making precision measurements of the large-scale brightness structure of the Sun is to date a largely unexplored area of research. The data set of measurements could contribute significantly to the understanding and monitoring of the Sun's luminosity variations. #