Binary Star Systems in Planetary Nebulae and their Relationship to Stellar Evolution: Modeling Two New Binary Systems

The aim of this research was to learn more about close binary star systems and how they influence the formation of planetary nebulae at the end of a star’s life. These systems are produced by a common envelope phase where they share the same atmosphere and spiral closer together, causing stronger interactions between the stars. Properties of these systems can be used to better understand Type 1A supernovae, cataclysmic variable stars, and gravitational waves. There are 70 of these close binary star systems known, of which fewer than 20 have been modeled. This summer, models were generated for two of these systems, the central stars of Lo 16 and PHR 1510-6754. The parameters determined were masses, radii, temperatures, inclination, and separation of the stars. Both systems have an irradiation effect, with Lo 16 displaying a small eclipse. Possible solutions for both systems have been found, and at this time, the models indicate stellar parameters that are consistent with the expected ranges for these systems. Further work will aim for a more complete range of all possible parameters. Knowing the specific combination of parameters will lead to a better understanding of how these systems form, how they impact the shaping of the planetary nebula, and how they will continue to evolve in the future.