Dynamics of cold circumstellar gas in debris discs

• DOI: 10.1093/mnras/stae924
• Publication Date: 2024-04-17T02:58:17Z
• Authors: Can Cui; Sebastian Marino; Quentin Kral; Henrik Latter
• Keywords: Circumstellar disk; Gas dynamics

ABSTRACT Mounting observational evidence indicates that cold circumstellar gas is present in debris disc systems. This work focuses on various dynamical processes may undergo. We review five mechanisms can transport angular momentum and their applications to discs. These include molecular viscosity, hydrodynamic turbulence, magnetohydrodynamic (MHD) magnetized winds, laminar magnetic stress. find viscosity result α as high ≲0.1 for sufficiently low densities, while the Rossby wave instability a possible source of turbulence structure formation. argue vertical shear unlikely due long cooling times. The onset magnetorotational (MRI) dichotomous: low-density discs MRI be excited at mid-plane, high-mass it only operating z > 2 − 3H, if all. MHD wind stress rely configuration strength any background large-scale field, existence which uncertain possibly unlikely. conclude dominant mechanism its efficiency transporting vary from one system other, depending especially closely density. More detailed analyses shall performed future focusing representative, nearby