Fundamental Stellar Parameters from the CHARA Array

美国佐治亚州立大学高角分辨率天文中心(CHARA)在Mt.加利福尼亚州威尔逊。查拉阵列由六个1米口径的望远镜组成，排列成Y形，提供了从33米到331米长的15条基线。该阵列在可见光和近红外光谱区工作，在K和V波段的极限分辨率分别为1.6和0.4毫角秒。就其望远镜的数量和口径大小以及基线长度而言，查拉阵列是世界上同类设备中最强大的之一。Chara阵列由佐治亚州立大学(GSU)、NSF、W.M.凯克基金会和David and Lucile Packard基金会提供资金建造，准备进行广泛的观测计划，对恒星天体物理学产生广泛影响。该奖项将主要通过在阵列现场维持足够的科学、技术和运营人员来支持这些计划。查拉核心团队还开展了一系列合作，以更充分地利用阵列的科学能力。由于其非常高的角分辨率以及良好的灵敏度和UV平面覆盖率，Chara阵列将前所未有地获得所有温度的主序列星以及演化恒星的恒星直径测量。准确的低能见度测量将表征恒星的大气边缘变暗。年轻恒星物体的大小和形状将被绘制成地图。将测量造父变星的脉动及其边缘变暗，以直接校准宇宙距离阶梯中的这一重要梯级。连续谱和分子带观测将表征演化恒星大气中的尺度高度。围绕Be星的圆盘和从发光的蓝色变星、Wolf-Rayet星和相互作用的双星大量流出的圆盘将被探测和表征。在双星研究领域，该阵列将消除发现双星和测量其轨道运动的各种技术中不重叠选择效应的经典问题。它将解析它可以访问的大部分光谱双星，提供广泛分布在HR图中的恒星的质量、光度和半径的测量。重点将放在质量测定的准确性上，而不仅仅是更多质量一般的质量，以观测到年龄和金属丰度对恒星演化的影响。低质量、看不见的伙伴将在更广泛的双星系统中寻找。已知的太阳系外行星系统将被检查，以确保面对面的双星即使在低水平也不会污染样本。超越科学和智力目标的更广泛的影响存在于三个领域。首先，查拉正在积极培养干涉测量领域的下一代科技专家。格拉斯哥州立大学天文学研究生中有相当一部分正在攻读该阵列的博士学位。查拉的工作人员参加了所有NASA/喷气推进实验室迈克尔逊暑期学校。其次，Chara将通过将阵列图像(在某些情况下是实时的)纳入本科天文学课程来提高GSU广大和多样化的本科生社区的科学意识，该课程每学期招收约700名学生。将招募几名本科生参加远程观测和数据处理。第三，山上的查拉展览馆。威尔逊戏剧性地展示了历史悠久的20英尺迈克尔逊恒星干涉仪，该干涉仪在20世纪20年代用于100英寸望远镜。每年数以千计的观测者将有一个独特的机会互动地了解干涉测量如何探测恒星以揭示它们的表面和基本性质。***

AST 0307562McAlisterGeorgia State University's Center for High Angular Resolution Astronomy (CHARA) operates an interferometric array on Mt. Wilson, California. The CHARA Array consists of six 1-m aperture telescopes arranged in a Y configuration providing 15 baselines from 33 to 331 meters in length. The Array operates in the visible and near-infrared spectral regions with limiting resolutions of 1.6 and 0.4 milli-arcseconds at the K and V bands. In terms of the number and aperture size of its telescopes and the length of its baselines, the CHARA Array is among the most powerful facilities of its type in the world. Built with funds provided by Georgia State University (GSU), the NSF, the W.M. Keck Foundation, and the David and Lucile Packard Foundation, the CHARA Array is poised to undertake extensive observational programs having a broad impact on stellar astrophysics. This award will support these programs primarily by maintaining an adequate scientific, technical and operational staff at the Array site. The core CHARA team has also developed a number of collaborations to more fully exploit the Array's scientific capability. Because of its very high angular resolution and its good sensitivity and UV-plane coverage, the CHARA Array will have unprecedented access to stellar diameter measures for main sequence stars of all temperatures as well as for evolved stars. Accurate low-visibility measurements will characterize atmospheric limb darkening in stars. The sizes and shapes of young stellar objects will be mapped. Pulsations of Cepheid variables and their limb darkening will be measured to directly calibrate this important rung in the cosmic distance ladder. Continuum and molecular band observations will characterize scale heights in the atmospheres of evolved stars. Disks surrounding Be stars and massive outflows from luminous blue variable stars, Wolf-Rayet stars and interacting binaries will be detected and characterized. In the area of binary star studies, the Array will eliminate the classical problem of non-overlapping selection effects among the various techniques for discovering binary stars and measuring their orbital motions. It will resolve the majority of the spectroscopic binaries accessible to it, providing measurements of stellar mass, luminosity and radius for stars broadly distributed throughout the HR diagram. The emphasis will be on accuracy of mass determination, not just more masses of mediocre quality, to observationally detect the influence of age and metallicity on stellar evolution. Low-mass, unseen companions will be sought in wider binary systems. Known extrasolar planetary systems will be inspected to ensure that face-on binaries are not contaminating the sample even at a low level. Broader impact beyond the scientific and intellectual goals exists in three areas. First, CHARA is actively training the next generation of scientific and technical experts in the field of interferometry. A significant fraction of GSU astronomy graduate students are pursuing their PhD research with the Array. CHARA staff have participated in all of the NASA/JPL Michelson Summer Schools. Second, CHARA will enhance science awareness in the large and diverse undergraduate community at GSU by incorporating Array imagery (real-time in some cases) in undergraduate astronomy courses, which enroll approximately 700 students per semester. Several undergraduates will be recruited to participate in remote observations and data processing. Third, a CHARA Exhibit Hall on Mt. Wilson dramatically displays the historic 20-ft Michelson Stellar Interferometer, used at the 100-inch telescope in the 1920s. Thousands of visitors to the observatory grounds each year will have a unique opportunity to interactively learn how interferometry can probe stars to reveal their surfaces and fundamental properties. ***