Radial Velocity Properties of Binary CEMP-r/s Stars
Abstract
Low metallicity stars allow us to better understand the chemical evolution of the Milky Way. A large fraction of low metallicity stars show large enhancements in carbon. These stars are known as Carbon Enhanced Metal Poor stars (CEMP stars). A subgroup of these show enhancements of neutron-capture elements through both the slow (s) and rapid (r) neutron-capture processes, these stars are called CEMP-r/s stars. How these stars get their peculiar abundance patterns is currently unknown, but in similar types of stars it has been shown that mass transfer in binary systems plays a significant role in their abundance patterns. If binaries do play a significant role in the enhancement of CEMP-r/s stars, I expect to find a large fraction of the stars I am studying to be in binary systems. The goal of this project is to better understand what role binaries have in the formation and enrichment of CEMP-r/s stars. I have been analyzed optical spectra obtained over the past two years for a sample of CEMP-r/s stars by Dr. Terese T. Hansen at the McDonald Observatory. Using the astronomical image reduction software IRAF I have extracted radial velocity data to combine with literature data and use this to identify possible binary systems. The results of this appear to show a strong correlation between CEMP-r/s stars being in binary systems, with an optimistic estimate of 85.7 % of CEMP-r/s stars in this data may be binaries.
Citation
Cathey, Jared Lee (2021). Radial Velocity Properties of Binary CEMP-r/s Stars. Undergraduate Research Scholars Program. Available electronically from https : / /hdl .handle .net /1969 .1 /194421.