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，都是稀有且寿命短的恒星。然而，它们主导着星系的光度和化学演化，并为星际介质提供能量。因此，了解它们的结构和演变是很重要的。这可以通过确定它们在光度和有效温度(Tef)图上的位置来实现--即Hertzprung-Russell(HR)图--相对于给定质量的恒星在其一生中将遵循的理论进化“轨迹”。通常情况下，很难测量大质量恒星的TEFF，人们必须依赖恒星大气模型的估计。该项目的首席研究人员(PI)和她的学生将直接利用测量的恒星光度和直径得出Tef，后者使用高角度分辨率天文中心(CHARA)阵列的长基线光学干涉观测获得。总而言之，该团队将直接确定41个目标(11颗O星和30颗B星)的TEF，从而能够精确地限制关键恒星参数，并评估基于恒星大气模型的估计。两个附带项目将探索恒星风的影响，并测量快速旋转的恒星织女四的形状。该奖项还将允许该大学加入东南天文学研究协会(SARA)财团，提供访问全球机器人望远镜网络的机会。该奖项将支持本科生全年的研究经验，包括前往CHARA研讨会和冬季AAS会议。长基线光学干涉测量将允许PI和学生以前所未有的精度得出关键的恒星参数。查拉阵列是目前世界上唯一一台能够获得足够高的角分辨率来分辨遥远的O星和B星的干涉仪。与最近的盖亚任务提供的精确恒星距离一起，该团队将使用测量的角直径来计算准确的恒星半径。这些将与校准的分光光度法相结合，以计算准确的Teff值。这项提案中概述的研究计划旨在为具有统计意义的O和B星样本提供一种可靠的恒星大气模型测试，该模型具有精确的观测确定参数。这项工作将进一步创建大质量恒星的低分辨率光学光谱库，因为历史上在这一领域没有大量数据。这一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智力优势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.