Peter Quigley

Western University

Peter Quigley is a second-year Master’s student at Western University, working under the supervision of Professor Carol E. Jones. His project focuses on simulating the evolution of viscous disks around massive, rapidly rotating stars using custom-built hydrodynamics code.

Be stars are a special class of B stars, the second most massive stars, which rotate close to the critical velocity where their outer layers are no longer supported by pressure. Due to a phenomenon at the surface, material is continuously ejected from the equator into orbit around the star, gradually forming a hot, viscously coupled ‘decretion’ disk. As the disk is constantly supplied with new material from the inner edge, angular momentum is transported outwards, causing the disk to grow. In many cases, a binary companion orbits the Be star and feeds off the decreting material in repeating energetic events.

Because of the unique feeding mechanism of their disks, Be stars serve as important checks on astronomers’ understanding of stellar evolution, fluid dynamics, and orbital mechanics. Peter’s project aims to closely examine the angular momentum lost by the star to the disk and track its flow throughout the disk’s evolution. By measuring the amount of angular momentum that flows away from the star, Peter hopes to better constrain the processes at the surface that keep the star rotating near the critical rate. He aims to achieve this by using a 3D hydrodynamics code to build a number of ‘typical’ Be binary systems, each with a preconstructed disk, and recording the position and velocity of particles that are accreted onto the primary or secondary star and those ejected from the simulation entirely. This approach allows precise measurement of how orbital parameters, initial disk conditions, and injection rates can change accretion flows in these fascinating stellar systems.