The Chemical Compositions of Wolf-Rayet WC Type Stars in the Large Magellanic Cloud

We have begun modeling the UV, optical, and near-IR spectra of Wolf-Rayet (WR) stars to better understand their evolution. WR stars are the evolved He-burning descendants of the most massive O-type stars. Their outer hydrogen layers have mostly been stripped away, revealing the stars' evolved cores. WRs are classified into three different subclasses, based upon their optical spectra: WN stars, which show strong emission lines of helium and nitrogen; WC stars, which show strong emission lines of carbon; and WO stars, which are very similar to WC stars, but also have very strong high-excitation oxygen lines (i.e., O VI). Now, there is a question over whether WOs are actually more chemically evolved than the WCs. By modeling these stars' spectra, we can determine their chemical composition and thus answer this, as oxygen abundances should increase only near the end of core He-burning. We have started the first phase of this work by evaluating the spectra of 4 WCs in the Large Magellanic Cloud (LMC). Here we present the modeled WC stars and discuss our findings. This work is supported through the NASA Astrophysics Data Analysis Program 80NSSC18K0729 as well as a grant from the Space Telescope Science Institute (GO-13781).