Seismological Investigations of Compact Objects

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

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.