Protostellar Disk Formation Regimes: Angular Momentum Conservation versus Magnetic Braking

Hsi-Wei Yen^1*, Yueh-Ning Lee^2,3,4

¹Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan
²Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan
³Center of Astronomy and Gravitation, National Taiwan Normal University, Taipei, Taiwan
⁴Physics Division, National Center for Theoretical Sciences, Taipei, Taiwan

* Presenter:Hsi-Wei Yen, email:hwyen@asiaa.sinica.edu.tw

The physical properties of protostellar disks, such as mass and size, are likely closely related to the planet formation process. Several mechanisms have been proposed to influence disk properties during star formation. To observationally examine these theories, we have been measuring disk properties and comparing them with magnetic fields, turbulence, gas kinematics, and stellar mass in various systems. In this presentation, I will summarize the observational results on the relationships between disk properties and physical conditions in protostellar sources and discuss key mechanisms determining disk properties. Our result highlights the significant role of non-ideal MHD effects, in particular ambipolar diffusion, and demonstrates that theoretical predictions from the combination of hydrodynamics and non-ideal MHD can explain the observed size distributions.

Keywords: Magnetohydrodynamics, Star formation, Protostar, Circumstellar disk