Picturing the faces of stars: limb-darkening models vs. interferometer measurements

该奖项旨在通过光学干涉测量和光谱学研究数百颗恒星。干涉测量结合来自不同望远镜的光波，产生非常高的角分辨率图像。这使得天文学家能够记录恒星盘上的亮度变化。中心显示的是星星更深、更温暖的层，而边缘显示的是更浅、更冷的物质。这种效应被称为边缘变暗。该小组还将记录光谱，测量单个化学元素发射或吸收的光。 这使得能够推导出干涉测量法尚未提供的恒星基本参数，例如恒星的整体光度和化学成分。所有数据将用于确定恒星直径和温度分布，并测试恒星天体物理学模型。数据和建模代码将发布到公共数据库。两名研究生将接受干涉测量和建模技术的培训。该小组将使用NPOI（海军原型光学干涉仪）和CHARA（高角分辨率阵列中心）干涉仪获得亚毫弧秒分辨率的图像。他们将用阿帕奇点天文台和格鲁吉亚州立大学的望远镜收集中等分辨率的光谱学。 他们将使用几个大气模型来探索三维效应和非局部热力学平衡（NLTE）效应。该项目将为100颗恒星和至少三种不同的模型运行精确的模型网格。恒星大气模型代码SATLAS将完全开放源代码，更新微观物理和NLTE改进。该代码和3D辐射流体力学STAGGER将通过与行业合作伙伴的合作，由图形处理器单元加速。

This award is made to study hundreds of stars with optical interferometry and spectroscopy. Interferometry combines light waves from different telescopes and produces very high angular resolution images. This allows astronomers to record the brightness variations across a stellar disk. The center shows deeper and warmer layers of a star, whereas the edges show shallower and cooler material. This effect is called limb-darkening. The group will also record optical spectra, which measure light emitted or absorbed by individual chemical elements. This enables derivation of fundamental parameters of the stars not already provided by interferometry, such as overall stellar luminosity, and chemical composition. All the data will be used to determine stellar diameters and temperature profiles and to test stellar astrophysics models. The data and modeling codes will be released to a public database. Two graduate students will be trained in both interferometric and modeling techniques.The team will use the NPOI (Naval Prototype Optical Interferometer) and CHARA (Center for High Angular Resolution Array) interferometers to obtain sub-milliarcsecond resolution images. They will collect moderate-resolution optical spectroscopy with Apache Point Observatory and Georgia State University telescopes. They will use several atmospheric models to explore three-dimensional effects and non-local thermodynamic equilibrium (NLTE) effects. The project will run precise model grids for a hundred stars and at least three different models. The stellar atmosphere model code SATLAS will be made fully open-source with updated microphysics and NLTE refinements. This code and the 3D radiative hydrodynamic STAGGER will be accelerated by Graphic Processor Units through partnerships with industry collaborators.