Collaborative Research Using High Mass Binaries to Resolve the Mass Discrepancy: Taking Things to the Extreme

AST-0506577菲利普·梅西洛厄尔天文台使用高质量双星解决质量离散问题的合作研究：把事情做到极致摘要一项观测计划将被实施，以确定最大质量恒星的质量。这项工作的动机是，用演化模型计算的高质量恒星的质量与用大气参数计算的质量之间的差异（2 ~ 3倍）（即，从巴尔末轮廓结合距离，红化，和测热星等的表面重力）。因此，要么问题仍然存在于大质量星星演化的理论中（重要的/未知的物理复杂性可能没有被包括在内），要么问题仍然存在于光谱方法中（可能使用了不正确的表面重力、光度、距离等）。为了解决这个问题并确定差异的来源，O型双星的质量将通过分析食双线分光双星（特别注意周期为3-5天的双星，因此没有相互作用）直接测量。在第一年，将对银河系和麦哲伦星云中的年轻星协和星团进行光度测量，以寻找食双星。第二年将获得候选人的径向速度。第三年将用于寻找轨道解，并计算光谱和演化质量，以与结果进行比较。测光数据（北方场的获取和北方和南方目标的还原）将是国家本科生研究天文台的一个关键项目的一部分。北方亚利桑那大学本科生研究经验计划和麻省理工学院野外营地的本科生将帮助光谱观测和轨道解决方案。

AST-0506577Philip MasseyLowell ObservatoryCollaborative Research Using High Mass Binaries to Resolve the MassDiscrepancy: Taking Things to the ExtremeABSTRACTAn observational program will be undertaken to determine the masses of the most massive stars.The work is motivated by significant (factors of two to three) differences in the masses of high massstars derived from evolutionary models compared with those calculated from atmosphericparameters (i.e, surface gravities from Balmer profiles combined with distance, reddening, andbolometric magnitudes). Thus, either problems remain with theories of high mass star evolution(important/unknown physical complications may have not be included), or with the spectroscopicapproach (incorrect surface gravities, luminosities, distances, etc. may be being used). To resolvethe question and ascertain the source of the discrepancy, the masses of binary O stars will bedirectly measured from an analysis of eclipsing double-lined spectroscopic binaries (specialattention will be paid to those with periods 3-5 days which have therefore not interacted). In thefirst year, young associations and clusters in the Milky Way and Magellanic Clouds will bephotometrically surveyed to find eclipsing binaries. Radial velocities for candidates will be obtainedin the second year. The third year will be used to find the orbit solutions, and to calculatespectroscopic and evolutionary masses for comparison with the results.This project includes a significant outreach and undergraduate research component. Thephotometric data (its acquisition for the northern fields and reduction for both northern and southerntargets) will be part of a key project of the National Undergraduate Research Observatory.Undergraduate students in Northern Arizona University Research Experiences for Undergraduatesprogram and MIT field camp will help with the spectroscopic observations and orbit solutions.