An Investigation of Post-Main-Sequence Mass Loss Using Fragile Binaries

在这个项目中，Oswalt和Holberg博士将对相距甚远的“脆弱双星”进行研究，这些双星包含正常的低质量主序星和遥远的无相互作用的白色矮伴星。随着恒星演化到白色矮星阶段，大多数恒星失去了超过一半的原始质量。 这种从初始质量到最终质量的关系是我们理解恒星演化以及物质如何循环进入星际介质的最薄弱环节之一。它对天体物理学的许多不同领域也具有特殊的重要性，例如球状星团的年龄和距离测定，研究星系的化学演化，以及了解银河系残余白色矮星记录的星星形成的历史。几十年来，人们已经知道太阳型恒星的色球活动随着年龄的增长而下降。 奥斯瓦尔特博士和他的合作者最近已经证明，这种趋势在银河系圆盘的预期年龄附近是有效的。 其他的工作已经证明恒星的年龄可以通过等时线拟合在色星等图中，或者通过简单的光度观测获得的恒星自转速率来确定。 在适当的情况下，这些技术将在这里被应用，以确定一个样本的宽分离双星的白色矮星的年龄。白色矮星的年龄跨越了太阳系的整个历史，可以从它们的观测温度中确定。从双星的总年龄中减去白色矮星伴星的年龄，就可以得到它的祖先主序星的寿命和初始质量。 通过这种方式，他们将根据经验校准白色矮星的初始到最终质量关系，至少达到太阳的年龄。 佛罗里达物理空间科学技术系是美国最大的天文学相关本科项目之一，2007年秋季招收了142个专业。大约一半是妇女和/或少数民族。 本科生将参与该项目的各个方面，从东南天文学研究协会（SARA）0.9米和佛罗里达技术0.8米望远镜的数据采集，到向科学界展示我们的结果。两名研究生也将进行与本项目直接相关的论文项目。 一名博士后研究员将与Oswalt和Holberg博士以及学生密切合作，通过等时线技术为每个宽双星系统得出独立的年龄测定。 合作PI Holberg将领导将该项目获得的关于宽双星的白色矮星组成部分的物理数据纳入亚利桑那大学白色矮星数据库的工作，该数据库被国际天文学界和公众广泛使用。 该项目的结果将通过佛罗里达理工学院天文台天文学/天体物理学系列讲座、AAS Shapley讲座和其他媒体纳入天文学课程并向公众公布。 预计K-12学生将通过全球动手宇宙项目参与该项目的数据采集阶段。

In this project, Drs. Oswalt and Holberg will undertake a study of widely separated "fragile binary stars" that contain normal lower mass main sequence stars with distant noninteracting white dwarf companions. As stars evolve to the white dwarf stage, most lose well over half their original mass. This initial-to-final mass relation is one of the weakest links in our understanding of stellar evolution and how matter is recycled into the interstellar medium. It is also of special importance to a number of different areas in astrophysics such as age and distance determinations of globular clusters, studying the chemical evolution of galaxies, and also for understanding the history of star formation as recorded by the Galaxy's remnant white dwarfs. For several decades it has been known that stellar chromospheric activity declines with age in Solar-type stars. Dr. Oswalt and collaborators have recently shown evidence that this trend is valid to nearly the expected age of the Galactic disk. Other work has demonstrated stellar ages can be determined by isochrone fitting in color magnitude diagrams or via stellar rotation rates obtained from simple photometric observations. These techniques will be applied here, where appropriate, to determine the ages of a sample of wide separation binaries with white dwarfs. The ages of the white dwarfs themselves, which span the entire history of the Solar neighborhood, can be determined from their observed temperatures. And by subtracting the ages of the white dwarf companions from the total age of the binary yields its progenitor main sequence lifetime and initial mass. In this way, they will empirically calibrate the initial-to-final mass relation for white dwarf stars to at least the age of the Sun. The Florida Tech Department of Physics & Space Sciences is home to one of the largest astronomy-related undergraduate programs in the U.S. In autumn 2007 it enrolled 142 majors. About half are women and/or minorities. Undergraduates will be involved in all aspects of the project, from data acquisition with the Southeastern Association for Research in Astronomy (SARA) 0.9m and Florida Tech 0.8m telescopes, to presenting our results to the scientific community. Two graduate students will also conduct dissertation projects directly related to this project. A postdoctoral research fellow will work closely with Drs. Oswalt and Holberg and the students to derive an independent age determination for each of the wide binaries via the isochrone technique. Co-PI Holberg will lead the effort to incorporate the physical data on the white dwarf components of wide binaries obtained by this project into the University of Arizona White Dwarf Database, which is a widely used by the international astronomical community and general public. Results of this project will be brought into astronomy courses and to the public via the Florida Institute of Technology Observatory Astronomy/Astrophysics Lecture Series, AAS Shapley Lectures, and other media. It is also anticipated that K-12 students will participate in the data acquisition phase of the project via the Global Hands-On Universe project.