Seismological Investigations of Compact Objects

对于由普通气体构成的恒星，恒星地震学提供了利用共振力学特性来获得关于恒星内部结构和组成的天文学上有趣的信息的机会。对于白矮星来说，地震学提供了类似的机会，也提供了学习基础物理学的机会。例如，人们怀疑白矮星的电子简并核在冷却过程中结晶，但表明结晶的计算需要观测证实。在这个项目中，克莱门斯博士将确定ZZ Ceti恒星（脉动白矮星）的非径向脉动模式。他们的地震分析的第一步将通过两种新方法来完成。对于较亮的目标（V 15.5），将使用南方天体物理研究天文台（SOAR）望远镜上的古德曼光谱仪获得时间分辨光谱。线轮廓变化将用于测量其球形度，即使在较低的信噪比。对于较暗的恒星，将使用Goodman光谱仪或SOAR光学成像仪上的时间序列光度测量来测量组合模式的振幅，这些振幅可以用来识别它们的球形度。预计斯隆数字巡天计划发现的10-20颗最有趣的Ceti ZZ星的模式将在三年的努力中被确定。该项目将帮助支持在北卡罗来纳大学教堂山分校古德曼实验室从事最先进天文研究的研究生和本科生的不同群体。古德曼实验室专门为学生提供天文仪器的经验，培养下一代仪器制造商是社区的优先事项。

For stars made of ordinary gas, stellar seismology offers the opportunity to use resonant mechanical properties to derive astronomically interesting information about stellar interior structure and composition. For white dwarfs seismology offers similar opportunities as well as the chance to learn fundamental physics. For example, it is suspected that the electron degenerate cores of white dwarfs crystallize during cooling, but the calculations that suggest crystallization require observational confirmation. In this project, Dr. Clemens will identify non-radial pulsation modes in ZZ Ceti stars (pulsating white dwarfs). This first step in their seismological analysis will be accomplished through two new methods. For the brighter targets (V 15.5), time-resolved spectroscopy will be obtained with the Goodman spectrograph on the Southern Observatory for Astrophysical Research (SOAR) Telescope. Line profile variations will be used to measure their spherical degree, even at lower signal-to-noise ratios. For the fainter stars, time series photometry on the Goodman Spectrograph or the SOAR Optical Imager will be used to measure the amplitudes of combination modes, which can be used to identify their spherical degree. It is expected that the modes of 10-20 of the most interesting new ZZ Ceti stars discovered by the Sloan Digital Sky Survey will be identified during the three years of this effort.This project will help support a diverse group of graduate and undergraduate students engaged in state-of-the-art astronomical research in University of North Carolina at Chapel Hill's Goodman Laboratory. The Goodman Laboratory specializes in giving students experience in astronomical instrumentation and the training of the next generation of instrument builders is a priority of the community.