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

在这个项目中，dr。奥斯瓦尔特和霍尔伯格将对广泛分离的“脆弱双星”进行研究，这些“脆弱双星”包含正常的低质量主序星和遥远的不相互作用的白矮星伴星。当恒星演化到白矮星阶段时，大多数会失去超过原来一半的质量。这种从初始到最终的质量关系是我们对恒星演化和物质如何循环进入星际介质的理解中最薄弱的环节之一。它在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的确定，研究星系的化学演化，以及了解银河系残余白矮星所记录的恒星形成历史。几十年来，人们已经知道，在太阳型恒星中，恒星色球层的活动随着年龄的增长而下降。奥斯瓦尔特博士及其合作者最近提供的证据表明，这种趋势对银河系盘的预期年龄几乎是有效的。其他工作已经证明，恒星年龄可以通过等时拟合色星等图或通过简单的光度观测获得的恒星旋转速率来确定。在适当的地方，这些技术将在这里被应用，以确定具有白矮星的宽距离双星样本的年龄。白矮星本身的年龄跨越了太阳附近的整个历史，可以从观测到的温度来确定。通过从双星的总年龄中减去白矮星伴星的年龄，就得到了它的祖主序列的寿命和初始质量。通过这种方式，他们将根据经验校准白矮星的初始到最终质量关系，至少与太阳的年龄相当。佛罗里达理工大学物理与空间科学系是美国最大的天文学相关本科专业之一。2007年秋天，它招收了142个专业。大约一半是女性和/或少数民族。本科生将参与项目的各个方面，从使用东南天文研究协会（SARA） 0.9米望远镜和佛罗里达理工大学（Florida Tech） 0.8米望远镜获取数据，到向科学界展示我们的成果。两名研究生也将进行与此项目直接相关的论文项目。博士后研究员将与博士密切合作。Oswalt和Holberg以及学生们通过等时线技术得出了每个宽双星的独立年龄测定。Co-PI Holberg将领导这项工作，将该项目获得的关于宽双星白矮星组成部分的物理数据纳入亚利桑那大学白矮星数据库，该数据库被国际天文学界和公众广泛使用。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讲座和其他媒体向天文学课程和公众介绍。预计K-12学生将通过全球动手宇宙项目参与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.