Collaborative Research: RUI: Tracing the Spectropolarimetric History of Circumstellar Structures from High-Mass Stars through Supernovae

合作研究：RUI：追踪从大质量恒星到超新星的绕星结构的光谱偏振历史

• 批准号: 0807664
• 负责人: Richard Ignace
• 金额: $ 61.7万
• 依托单位: East Tennessee State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0807664&HistoricalAwards=false
• 关键词: Collaborative; Research; RUI; Tracing; Spectropolarimetric

Though their field was once thought to be reasonably well-understood, astronomers in the massive-star community are now faced with a number of new and fundamental questions about the non-spherical character of stellar mass loss. The nature and extent of wind clumping remains an unsolved problem; recent studies suggest that due to this clumpiness, O star mass-loss rates should be revised downward by an order of magnitude or more. In addition, a growing body of evidence shows that magnetic fields can influence the geometry of mass loss in hot star winds in unanticipated ways. The effects of stellar rotation on the structure and formation of disks around some main sequence and post-main sequence massive stars are still not fully understood. Meanwhile, detailed observations of supernovae reveal that many more core-collapse objects interact extensively with aspherical circumstellar environments than previously realized, and signatures of this interaction may be mined for clues to the mass-loss histories of massive supernova progenitors.This project is a comprehensive study of clumpy and aspherical structures in the circumstellar media of massive stars and supernovae. Motivated by access to high-resolution spectropolarimetric data and using an established Monte Carlo radiative transfer code, Drs. Ignace and Hoffman, and their team, will construct simulations of variable line and continuum polarization in the stochastically clumped winds of Wolf Rayet, luminous blue variable, and O stars; in the disks and rotating magnetospheres of other active stars; and in core-collapse supernovae interacting with their immediate environments. They will also develop algorithms that will allow the modeling code to simulate line polarization arising from the Zeeman and Hanle effects from the circumstellar fields of magnetized stars. The investigators have broad experience in both radiation transport techniques and interpreting spectropolarimetric observations of hot star winds and interacting supernovae. By confronting detailed 3D models of these systems with multiwavelength and polarimetric data, the goal is a better understanding of how the mass-loss history of main-sequence and evolved massive stars can be extracted from their observation and those of core collapse supernovae.The project includes a unique outreach program, Promoting Careers in Science, through which Drs. Ignace and Hoffman will each implement innovative strategies for improving science education and literacy in their respective communities. Dr. Ignace will reach out to school counselors to enhance science education among Appalachian middle- and high-school students. Dr. Hoffman will partner with the University of Denver's Women's College to create new entry points into the scientific career 'pipeline' for non-traditional female undergraduate students. In addition, Dr. Ignace will continue supervising undergraduate research projects both through East Tennessee State University and through involvement in an REU site program. The bulk of the 5-year funding will go to support the training and professional development of a postdoctoral researcher at East Tennessee State University and a graduate student at the University of Denver who will be trained in the theoretical modeling of radiation transfer.

虽然他们的领域曾经被认为是合理的理解，天文学家在恒星社区现在面临着一些新的和基本的问题，关于恒星质量损失的非球形特征。风聚集的性质和程度仍然是一个未解决的问题;最近的研究表明，由于这种聚集，O型星星的质量损失率应该向下修正一个数量级或更多。此外，越来越多的证据表明，磁场可以以意想不到的方式影响热星星风中质量损失的几何形状。恒星自转对某些主序星和后主序星大质量恒星周围盘的结构和形成的影响仍然没有完全了解。与此同时，对超新星的详细观测揭示了更多的核心坍缩天体与星周非球面环境的广泛相互作用，这种相互作用的特征可以用来寻找大质量超新星祖先的质量损失历史的线索。本项目是对大质量恒星和超新星的星周介质中的球状和非球面结构的综合研究。受高分辨率分光偏振测量数据的启发，并使用已建立的蒙特卡罗辐射传输代码，伊尼亚斯和霍夫曼博士及其团队将模拟沃尔夫·拉叶星、亮蓝变星和O星的随机聚集风中的可变线和连续偏振;其他活跃恒星的磁盘和旋转磁层;以及核心坍缩的超新星与周围环境的相互作用。他们还将开发算法，使建模代码模拟线极化所产生的塞曼和汉勒效应从围磁场的磁化恒星。研究人员在辐射传输技术和解释热星星风和相互作用的超新星的分光偏振观测方面都有广泛的经验。通过将这些系统的详细3D模型与多波长和偏振数据进行对比，目标是更好地了解如何从观测和核心坍缩超新星中提取主序星和演化大质量恒星的质量损失历史。该项目包括一个独特的推广计划，促进科学事业，通过该项目，伊尼亚斯博士和霍夫曼博士将各自实施创新战略，以改善各自社区的科学教育和扫盲。伊尼亚斯博士将接触学校辅导员，以加强阿巴拉契亚初中和高中学生的科学教育。霍夫曼博士将与丹佛大学女子学院合作，为非传统的女本科生创造进入科学职业“管道”的新切入点。此外，伊尼亚斯博士将继续通过东田纳西州立大学和通过参与REU现场计划来监督本科生研究项目。5年期资金的大部分将用于支持东田纳西州立大学的博士后研究员和丹佛大学的研究生的培训和专业发展，他们将接受辐射转移理论建模的培训。