The Wolf's Bite: Investigating The Shapes Of Colliding Wind Regions In Wolf-Rayet Binary Star Systems

Wolf Rayet (WR) stars are a type of evolved star at the end of its life that is shedding large amounts of mass from its outer layer. Sometimes, these stars form binary systems with very large main sequence stars, which cause even more gas from the WR star to be shredded. This interaction is thought to be the cause of the catastrophic cosmic gamma ray burst (GRB) events, where gamma rays, the most energetic form of the electromagnetic spectrum, are shot out across extreme distances. This explosion can depend on how much mass is being lost by the object, which can be discovered by examining the interaction between the two stars in the binary, particularly the gas being shed by the WR partner. The polarization of light coming from these systems is a great way to examine the various behaviors and qualities of different binary objects.
 

That was the goal of this project, where I examined the object WR21 and WR31 in detail. I did this by using data our research team had collected from the RSS Spectropolarimeter located at the SALT observatory in South Africa. Then, using the coding program Python, I was able to examine the polarization of different lines throughout the orbital period that showed up in the spectrum (corresponding to what elements were present). I was able to examine various spectral lines of interest, such as C IV at 5805 angstroms and N IV at 7125 angstroms, and to see how these emission lines behaved differently from the continuum and to locate which place in the system they formed. From this, further analysis can be conducted to examine if the mass loss of this particular object is enough for it to be a GRB progenitor.