The Life Cycles of Interacting Binary Stars

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。在这个项目中，宾夕法尼亚州立大学的梅塞德斯·理查兹博士将使用光谱分析、合成光谱、断层扫描和流体动力学模拟来研究相互作用的双星生命周期的早期阶段。近距离双星的演化顺序从两颗分离恒星的形成开始，到包含至少一个致密天体（如新星、超新星、x射线双星、脉冲星双星）的演化系统结束。从早期到晚期的转变取决于初始传质速率，它受恒星填充其罗氏表面时的结构、假设轨道角动量和系统质量守恒的程度以及伴星对气体吸积的响应的影响。双星演化模型需要知道这个初始质量损失率，因为供体将以这个速率失去气体，直到初始质量比被逆转。Richards将使用对气流和其他吸积结构的直接测量来确定在缓慢传质阶段的双星的传质速率、气体密度和气体温度的可靠估计。她将采用一种新的方法来分离气流、吸积盘和任何热点的单独光谱贡献。用她的合成代码计算合成光谱，并与观测到的光谱进行比较，得出吸积流各组分的物理性质。导出的气体性质将用于生成双星的流体动力学模拟。最后，多普勒断层扫描将用于可视化传输的气体，并检查导出参数的质量。这项研究的结果有望对相互作用双星的整个领域产生影响。理查兹博士已经向天文学界免费发布了她的新光谱合成代码，其他天文学家也在使用该代码后发表了论文。她还拥有丰富的外展经验，她将继续致力于外展活动，并与研究生，本科生，K-12学生，教师，夏季高中充实计划和公众保持众多互动。她也有机会在全国各地旅行，谈论她的研究和流行的天文学话题。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).In this project, Dr. Mercedes Richards of the Pennsylvania State University will use spectroscopic analysis, synthetic spectra, tomography, and hydrodynamic simulations to study the early stages of the life cycle of interacting binary stars. The evolutionary sequence for close binaries begins with the formation of two detached stars and ends with evolved systems containing at least one compact object (e.g., novae, supernovae, X-ray binaries, binary pulsars). The transition from the early to late stages depends on the initial mass transfer rate, which is influenced by the structure of the star when it fills its Roche surface, the degree to which orbital angular momentum and system mass are assumed to be conserved, and the response of the companion star to the accretion of gas. Binary evolution models require knowledge of this initial mass loss rate since the donor will lose gas at this rate until the initial mass ratio has been reversed.Dr. Richards will use direct measurements of the gas stream and other accretion structures to determine reliable estimates of the mass transfer rate, gas densities, and gas temperatures for binaries in the slow mass transfer phase. She will apply a new approach to isolate the separate spectroscopic contributions of the gas stream, accretion disk, and any hot spots. Synthetic spectra will be calculated with her synthesis code and compared with observed spectra to derive the physical properties of the separate components of the accretion flows. The derived gas properties will be used to generate hydrodynamic simulations of the binary. Finally, Doppler tomography will be used to visualize the transferred gas and to examine the quality of the derived parameters.The results of this research are expected to have implications for the entire field of interacting binaries. Dr. Richards has already released her new spectrum synthesis code freely to the astronomical community, and other astronomers have published papers after using this code. She also has extensive outreach experience, and she will continue her commitment to outreach activities and maintain numerous interactions with graduate students, undergraduates, K-12 students, teachers, summer high school enrichment programs, and the general public. She also has opportunities to travel around the country to talk about her research and popular astronomy topics.