|Time:||星期二, 11月 03, 2020, 10:30am|
|Title:||Introduction to Warped Accretion Discs|
|Speaker:||Hongping Deng (Cambridge)|
Online via Zoom (Meeting ID: 920 6438 7397 PW: 201103)
Warped accretion discs are common around black holes and stars. There is growing indirect observational evidence for warped circumstellar discs around young stars, indicated by shadows cast by the warps. I will briefly review the rich warped disc dynamics, including warp diffusion, bending wave propagation and disc breaking. I will focus on a hydrodynamic instability due to resonance between pairs of inertial waves and warp induced shear flow. The ensuing turbulence, captured for the first time in a global simulation, damps relative orbital inclinations and leads to a decrease in the angular momentum deficit. As a result, the warp undergoes significant damping within one bending-wave crossing time. Observed protoplanetary disc warps are likely maintained by companions or aftermath of disc breaking.
Host: Xuening Bai