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

这项提议将继续进行一项正在进行的努力，以精确测量整个太阳圆盘的大尺度太阳表面亮度变化。大熊太阳天文台已经建造了一台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数据，PI将进行一些研究：1)PI将把测量到的随纬度和时间变化的亮度变化与随时间变化的太阳常数进行比较。从光度计获得的更完整的空间信息将被用来更好地理解导致太阳光度短期和长期变化的物理机制。例如，测量的依赖于纬度和&gt；的平均亮度结构(这里&gt；是通常的日心角)，与测量的光斑对比函数一起，可以用来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(使用我们的光度学数据)限于活动纬度，那么当空间太阳常数测量不可用时，像这里建议的那些精确的地面测量可以很好地替代基于空间的太阳常数测量。2)PI将更好地测量极-赤道温差，努力将依赖于周期的磁信号与可能与时间无关的差动旋转信号分开。这样的测量将限制太阳差异自转的模型。3)PI将精确测量太阳极点附近的亮度变化，以便更好地了解极地磁场和极地光斑。到目前为止，精确测量太阳的大尺度亮度结构在很大程度上是一个尚未探索的研究领域。这组测量数据可以大大有助于理解和监测太阳的光度变化。#

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. #