The Large Influence of Small Tilts on Protoplanetary Disks in Binary Star Systems
J. J. Zanazzi (CITA)
September 23, 2021
Abstract: ALMA has revealed an overwhelming number of highly warped protoplanetary disks, where the inner disk lies on an orbital plane highly misaligned to the outer disk. However, a prediction of tilted protoplanetary disk theories is even small misalignments can have a significant impact on the long-term inclination evolution of the disk. In this talk, we will go over the prediction and observational validation of theories regarding small tilts of protoplanetary disks in binary star systems. We will discuss why a protoplanetary disk orbiting two stars on an eccentric orbit can sometimes have its inclination grow to a 90 degree angle with the binary orbital plane, and the protoplanetary disks observed to lie in this polar-aligned state. We will examine how the gravitational torque on a protoplanetary disk from a binary companion can cause a planet to form around a backwards-spinning star, and how the spin directions of stars within numerous exoplanetary systems can be explained by this disk torquing mechanism. We will also discuss work on oddball protoplanetary disks, such as KH 15D, and ongoing observational efforts to further test the robustness of theories involving tilted protoplanetary disks in binary star systems.