X-ray Emissions of Wolf-Rayet Stars. Nathan Wenzel & Dr. Nathan Miller Department of Physics and Astronomy University of Wisconsin - Eau Claire

Abstract Procedure and Results

Using a program called Spect 3D, control models of Using a computer program called Spect 3D developed The results from the O-star showed that optical O-stars, speci cally Zeta Puppis, were created and then depth, which is the measure of how opaque a compared with models of Wolf-Rayet stars. The models by Prism Computational Sciences, models were material is when radiation is passing through it, were made in a similar fashion comprising a three region is lower than the Wolf-Rayet star at similar shell surrounding the star consisting of a warm region created of the star’s stellar winds. A three region model photon energies. This means that in the Wolf- followed by the shock region of the stellar wind and Rayet star these particular X-ray emissions with nishing with another warm region. The X-ray emissions of was created which consisted of a warm region of the wind the given photon energy are less likely to be the winds were compared for these two types of stars. We seen. primarily looked at the optical depth of the wind, the followed by the X-ray producing shock region and intensity of the emissions, and the level of oxygen ions Also, there is a dierence in the resultant present in the wind. then followed by another warm region. Models of an intensity between the two stars. With the O-star (Zeta Puppis) were O-star there is more variance in the emitted used as control models to photon energies while the Wolf-Rayet star has a Background Figure 2. Sample of a model star compare with models cluster of photon emissions. Another notiable created using the computer program. created based on Wolf-Rayet dierence is that the photon energies present star (WR1) parameters. in the O-star are not as intense as the Wolf- O-stars, such as Delta After the models were made, they were uplaoded into a simulation Rayet star. Orionis in the Orion program that produced a variety of dierent graphs. These graphs constellation, are classi ed showed optical depth of the stellar wind, ionization fraction of as massive hot stars. oxygen ions, and the intensity of the X-rays produced in the shock Massive hot stars pass regions. through the Wolf-Rayet Figured below are the results of Figured below are results of the Acknowledgements stage as they progress the O-star (Zeta Puppis). Wolf-Rayet star (WR1). toward their eventual demise as supernovae. • We gratefully acknowledge Both the normal hot stars support from the UWEC Oce of and the Wolf-Rayet stars Research and Sponsored have extremely powerful Optical Programs through a Summer stellar winds, but Depth Research Experiences for surprisingly that while Undergraduates grant. We also O-stars produce strong wish to acknowledge Research X-rays, Wolf-Rayet stars are Corporation for funding the weak X-ray emitters. In initial development of this the massive hot stars, the project. X-rays are believed to be generated by shocks in Ionization • Andrew Johnson for the stellar winds of the Fraction technological help and program star caused by unstable manual. wind driving mechanisms. Figure 1. O star (Delta Orionis ) These mechanisms located in the constellation of involves radiation Orion. originating from the surface of the star pushing material outwards. The instablility of the driving mechanism causes the material to travel at dierent speeds. Faster moving material Intensity slams into slower moving material resulting in strong shocks. It is in these shock regions that the X-rays are believed to be produced.