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赛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。 密近联星的演化序列始于两颗分离恒星的形成，并以包含至少一个致密天体的演化系统结束（例如，新星，超新星，X射线双星，双星）。从早期阶段到后期阶段的过渡取决于初始质量转移速率，这是由星星的结构，当它充满它的洛希表面，轨道角动量和系统质量被假定为守恒的程度，以及同伴星星的气体吸积的反应的影响。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损失气体，直到初始质量比被逆转。理查兹博士将使用直接测量的气流和其他吸积结构，以确定可靠的估计质量转移速率，气体密度，气体温度的双星在缓慢的质量转移阶段。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。合成光谱将计算与她的合成代码和观察到的光谱比较，以获得吸积流的单独组件的物理特性。导出的气体性质将用于生成二元体的流体动力学模拟。最后，多普勒层析成像将被用来可视化传输的气体，并检查导出的参数的质量。这项研究的结果预计将有相互作用的双星的整个领域的影响。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这一代码后发表了论文。她也有广泛的外展经验，她将继续她的外展活动的承诺，并保持与研究生，本科生，K-12学生，教师，暑期高中充实计划，和广大公众的众多互动。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.