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

在这个项目中，奥斯瓦特和霍尔伯格博士将对广泛分离的“脆弱双星”进行研究，这些恒星包含正常的低质量主序恒星和遥远的非相互作用的白矮星伙伴。随着恒星演化到白矮星阶段，大多数恒星的质量损失了一半以上。这种从初始到最终的质量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。它对天体物理学中的一些不同领域也特别重要，例如球状星团的年龄和距离测定，研究星系的化学演化，以及理解星系残余白矮星记录的恒星形成历史。几十年来，人们已经知道，在太阳类型的恒星中，恒星的色球活动随着年龄的增长而下降。奥斯瓦特博士和他的合作者最近提出的证据表明，这一趋势在银河盘的预期年龄之前仍然有效。其他工作已经证明，恒星年龄可以通过色等图中的等时线拟合或通过简单的光度观测获得的恒星自转速度来确定。这些技术将在适当的情况下应用于这里，以确定具有白矮星的宽间隔双星样本的年龄。白矮星本身的年龄跨越了太阳附近的整个历史，可以根据它们观测到的温度来确定。通过从双星的总年龄中减去白矮星同伴的年龄，就得到了它的祖先主序列寿命和初始质量。通过这种方式，他们将从经验上将白矮星的初始到最终质量关系校准到至少太阳的年龄。佛罗里达理工学院物理与空间科学系是美国最大的天文学相关本科项目之一。2007年秋季，该学院招收了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方方面面，从使用东南天文学研究协会(SARA)的0.9米望远镜和佛罗里达理工大学的800米望远镜获取数据，到向科学界展示我们的成果。两名研究生还将进行与该项目直接相关的毕业论文项目。一名博士后研究员将与奥斯瓦特和霍尔伯格博士以及学生们密切合作，通过等时线技术得出每一颗宽双星的独立年龄确定。Pi Holberg联合研究员将牵头将该项目获得的关于宽双星的白矮星成分的物理数据纳入亚利桑那大学白矮星数据库，该数据库是国际天文学界和公众广泛使用的。该项目的成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讲座和其他媒体引入天文学课程并向公众公布。还预计，K-12年级的学生将通过全球动手宇宙项目参与该项目的数据获取阶段。

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.