Interferometric Modelling and Imaging of the Symbiotic Binary System, EG Andromedae

Symbiotic stars are a type of interacting stellar binary system consisting of a hot compact object (typically a white dwarf or sometimes a neutron star) and a cool companion (typically a cool giant star) orbiting around their common center of mass. These objects are generally characterized by orbital periods of 100s to 1000s of days and are surrounded by an optically thick dense circumstellar medium. Understanding the process of mass transfer in this type of binary system can improve our understanding of accretion processes and these systems potential evolution to Type Ia supernovae, By measuring the angular diameter and shape of the cool star using optical interferometry, it is possible to determine the star’s Roche-filing factor and thereby study whether mass-transfer is driven by winds or Roche-lobe overflow. Here, we use H-band interferometric observations from the Center for Higher Angular Resolution Astronomy (CHARA) Array to determine the angular diameter and shape of the secondary component of EG And system using OITOOLS, a Julia package for working with and simulating optical interferometric data. In addition to this, we present reconstructed images for the symbiotic binary system from select epochs. We discuss the implications of these results on the nature of mass-transfer in the system and how these conclusions relate to descriptions of the system made with other observational methods including ellipsoidal variations in light curves.