LEAPS-MPS: Constraining Stellar Structure and Evolution of Massive Stars with Optical Interferometry

大质量恒星，特别是O星和b星，非常罕见，寿命也很短。然而，它们支配着星系的光度和化学演化，并为星系间介质提供能量。因此，了解它们的结构和进化是很重要的。这可以通过确定它们在亮度和有效温度（Teff）图上的位置来完成，即赫茨普隆-罗素（HR）图，相对于给定质量的恒星在其一生中所遵循的理论进化“轨迹”。通常，对于大质量恒星来说，Teff很难测量，必须依靠恒星大气模型的估计。该项目的首席研究员（PI）和她的学生将直接使用测量的恒星光度和直径来获得Teff，后者使用高角分辨率天文学中心（CHARA）阵列的长基线光学干涉观测获得。总而言之，该团队将对41个目标（11个o型星和30个b型星）的Teff进行直接测定，从而对关键恒星参数进行精确限制，并对基于恒星大气模型的估计进行评估。两个附带项目将探索恒星风的影响，并测量快速旋转的蛇夫ζ星的形状。该奖项还将允许该大学加入东南天文学研究协会（SARA）联盟，为机器人望远镜的全球网络提供访问权限。该奖项将支持本科生全年的研究经历，包括前往CHARA研讨会和冬季AAS会议。长基线光学干涉测量法将允许PI和学生以前所未有的精度推导出关键的恒星参数。CHARA阵列是目前世界上唯一能够获得足够高的角分辨率来分辨遥远的O星和B星盘的干涉仪。加上最近盖亚任务提供的精确恒星距离，该团队将使用测量的角直径来计算精确的恒星半径。这些将与校准的分光光度法相结合，以计算准确的Teff。本提案中概述的研究计划旨在为具有统计意义的O星和b星样本提供具有精确观测确定参数的恒星大气模型的可靠测试。这项工作将进一步导致创建一个低分辨率的大质量恒星光谱库，因为历史上在这个领域没有大量的数据。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Massive stars, specifically O and B-stars, are rare and short lived. Nevertheless, they dominate the luminosity and chemical evolution of galaxies, and energize the intergalactic medium. It is thus important to understand their structure and evolution. This can be done by determining their positions on a plot of luminosity and effective temperature (Teff) - i.e., an Hertzprung-Russell (HR) diagram - relative to theoretical evolutionary "tracks" that stars of a given mass will follow over their lifetime. Ordinarily, Teff is difficult to measure for massive stars and one must rely on estimates from stellar atmosphere models. The Principal Investigator (PI) of this project and her students will derive Teff directly using measured stellar luminosities and diameters, with the latter obtained using long baseline optical interferometric observations with the Center for High Angular Resolution Astronomy (CHARA) array. All in all, direct determinations of Teff for forty-one targets (11 O-stars and 30 B-stars) will be carried out by the team, allowing precise constraints for key stellar parameters as well as an assessment of estimates based on stellar atmosphere models. Two side projects will explore the effects of stellar winds and measure the shape of the rapidly rotating star zeta Oph. The award will also allow the university to join the Southeastern Association for Research in Astronomy (SARA) consortium, providing access to a global network of robotic telescopes. This award will support a year-round research experience for an undergraduate student including travel to CHARA workshops and winter AAS meetings.Long baseline optical interferometry will allow the PI and students to derive key stellar parameters with unprecedented precision. The CHARA array is currently the only interferometer in the world capable of attaining sufficiently high angular resolution to resolve the disks of distant O and B- stars. Together with precise stellar distances provided by the recent Gaia mission, the team will use measured angular diameters to calculate accurate stellar radii. These will be combined with calibrated spectrophotometry to calculate accurate Teff. The research program outlined in this proposal seeks to provide a robust test of stellar atmospheric models with precise, observationally determined parameters for a statistically significant sample of O and B-stars. This work will further result in the creation of a low resolution optical spectral library for massive stars, as there is historically not a large amount of data in this area.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.