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

描绘恒星的面孔：临边变暗模型与干涉仪测量

• 批准号: 1616483
• 负责人: Fabien Baron
• 金额: $ 37.6万
• 依托单位: Georgia State University Research Foundation, Inc.
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1616483&HistoricalAwards=false
• 关键词: Picturing; faces; stars; limb; darkening

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.

该奖项旨在研究具有光学干涉法和光谱法的数百个恒星。干涉法结合了来自不同望远镜的光波，并产生非常高的角度分辨率图像。这使天文学家可以记录恒星磁盘上的亮度变化。该中心显示出恒星的更深，更温暖的层，而边缘则显示较浅，较冷的材料。这种效果称为肢体变形。该组还将记录光谱，该光谱测量了单个化学元素发出或吸收的光。 这使干涉法所没有提供的恒星的基本参数（例如总体恒星光度和化学组成）衍生。所有数据将用于确定恒星直径和温度曲线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和建模技术的培训。该团队将使用NPOI（海军原型光学干涉仪）和CHAR（高角度分辨率阵列中心）干涉仪的CHARA（中心）来获取子米利亚克秒的分辨率图像。他们将使用Apache Point天文台和佐治亚州立大学望远镜收集中分辨率的光谱。 他们将使用多种大气模型探索三维效应和非本地热力学平衡（NLTE）效应。该项目将用于一百颗恒星和至少三个不同型号的精确模型网格。恒星气氛模型代码SATLAS将通过更新的微物理和NLTE的精炼进行完全开源。该代码和3D辐射流体动力学交错将通过与行业合作者的合作伙伴关系来加速图形处理器单位。