The origin of chemically peculiar stars and non-zero eccentricity in evolved close binaries have been long-standing problems in binary stellar evolution. Answers to these questions may trace back to an intense mass transfer during AGB binary phases. In this talk, I will discuss two mass transfer modes in the AGB binaries and the transition between them. One mass transfer mode is Bondi-Hoyle-Lyttleton (BHL) accretion and the other is Wind-Roche-lobe overflow (WRLOF). We use AstroBEAR to solve radiation-hydrodynamic equations in 3D and calculate mass transfer rates in asymptotic-giant-branch (AGB) binaries with different binary separations. Accretion disks may form around the secondaries. Depending on the binary separation, a circumbinary disk or a spiral structure may appear in the simulation. The resulting mass transfer efficiency in our models is up to a factor of 8 times higher than what the standard BHL accretion scenario predicts, and the outflow gains up to 91% of its initial angular momentum when it reaches 1.3 binary separations. Consequently, some AGB binaries may undergo orbit shrinkage, and some will expand. The high mass transfer efficiency is closely related to the presence of the circumbinary disks.

I am now a CITA National fellow at the University of Alberta and working with Professor Natalia Ivanova. My main focus is on computational astrophysics and binary stellar evolution. Prior to this position, I worked with Professor Adam Frank and Professor Eric Blackman on AGB binaries and planetary nebulae. I obtained my Ph.D. in Physics in 2018 at the University of Rochester. My major during my undergraduate studies was Engineering Mechanics, and I got my Bachelor's degree at Tongji University.