U.S.-Australia Cooperative Research: Observational and Modeling Study of the Pulsating AGB Stars

0417772J。佛罗里达大学罗伯特·布赫勒该奖项使佛罗里达大学的J·罗伯特·布赫勒教授和他的团队与澳大利亚国立大学的彼得·伍德博士和他的团队在天体物理学方面的合作成为可能。他们都对变星感兴趣，特别是被称为“脉动渐近巨星(AGB)”的恒星。他们的合作得益于资源和专业知识的共享：这位澳大利亚合作者可以访问并完全熟悉关于变星的MARHO(大规模致密晕天体)天文数据档案，他对长周期变星的建模有着长期的兴趣和专业知识。美国的PI开发了独特的专门的计算机工具来分析观测数据，他在恒星脉动的(非线性)数值流体动力学建模方面拥有长期的经验。在这次合作中要研究的不规则脉动恒星的重要群体包括西处女座类型、RV金牛座类型、半规则变星和米拉区域的一些变星。这些明亮的变星在星团和矮星系的观测研究中发挥着越来越重要的作用，在这些星系中，经典造父变星等标准蜡烛可能很少见。研究人员的“星震学”目标是从观测到的不规则光曲线分析中提取独特的、定量的信息。还计划对一种假设进行测试，即单一的共振机制是这些恒星不规则脉动的核心。此外，这项研究将为这些恒星不确定的进化状态提供新的线索。新的观测数据，适应于非线性动力学的新的分析方法，以及数值对流水码的进展，为这一研究提供了一个及时的状态。BROADER IMPACT博士后研究员和双方的研究生将从拟议的国际合作中受益。该项目还具有更广泛的影响，因为他们开发的技术在其他研究领域也非常有用，从天文学到非线性动力学再到医学。PI的两个代码正在变得用户友好和公开访问：TIFRAN是一种时频分析，作为语音障碍、耳鼻喉科和神经学等的诊断工具在医学上有应用；FLOWRECON是一种从时间序列重建的流，在非线性动力学研究中有广泛的应用。在PI的监督下，一名本科生开始开发一个关于变星的热门音视频网站。本科生的大型非微积分物理课程的教学为PI提供了将天体物理学，特别是他自己的研究带到课堂上的机会。

OISE 0417772J. Robert Buchler, University of FloridaThis award makes possible a collaboration in astrophysics between Prof. J. Robert Buchler and his group at the University of Florida, and Dr. Peter Wood and his group at the Australian National University. They share an interest in variable stars, particularly in the type referred to as "pulsating Asymptotic Giant Branch (AGB) stars." Their collaboration benefits from sharing of resources and expertise: the Australian collaborator has access to, and is thoroughly familiar with, the MACHO (Massive Compact Halo Objects) astronomical data archive on variable stars, and he has longstanding interest and expertise in the modeling of long-period variables. The American PI has developed unique and specialized computer tools for the analysis of the observational data, and he has longstanding experience with the (nonlinear) numerical hydrodynamical modeling of stellar pulsations. SCIENTIFIC MERITThe important groups of irregularly pulsating stars to be studied in this collaboration include the W Virginis type, the RV Tauri type, the Semi-regular variable stars and some of the variable stars in the Mira region. These bright variable stars are playing an increasingly important role in the observational study of star clusters and dwarf galaxies where standard candles such as classical Cepheid stars may be rare. The investigators' 'asteroseismological' goal is to extract unique, quantitative information from the analysis of the observed irregular light curves. A test is also planned of the hypothesis that a single resonant mechanism is at the heart of the irregular pulsations of these stars. Further, the study will shed new light on the uncertain evolutionary status of these stars. New observational data, novel methods of analysis adapted from nonlinear dynamics, and progress in numerical convective hydrocodes lend such a study a timely status.BROADER IMPACT Postdoctoral fellows and graduate students on both sides will benefit from the proposed international collaboration. The project also has a broader impact, in that the techniques they have developed are very useful in other research areas as well, ranging from astronomy to nonlinear dynamics to medicine. Two of the PI's codes are being made user-friendly and publicly accessible: TIFRAN, the time-frequency analysis, has medical applications as a diagnostic tool for speech disorders, otolaryngology and neurology among other things, and FLOWRECON, the flow reconstruction from a time-series, has wide applications in nonlinear dynamics research. Under the supervision of the PI, an undergraduate student has started developing a popular audio and video website on variable stars. The teaching of the large undergraduate noncalculus Physics class provides the PI with the opportunity to bring astrophysics, and his own research in particular, to the classroom.