2016/08/09 by Donna Rodgers-Lee, Tom P. Ray, T. P. Ray +2
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Classical mechanics #Instability #Magnetohydrodynamics #Magnetorotational instability #Mechanics #Nuclear physics #Physics #Planet #Plasma #Protoplanetary disk #Stellar, planetary, and galactic studies #astro-ph.EP #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stw1980
13 pages, 12 figures, 1 table, accepted for publication in MNRAS
arxiv created 2016/08/09 · openalex publication_date 2016/08/09 · openalex created_date 2016/08/23 · arxiv updated 2016/12/07 · openalex updated_date 2026/08/05
The redistribution of angular momentum is a long standing problem in our understanding of protoplanetary disc (PPD) evolution. The magnetorotational instability (MRI) is considered a likely mechanism. We present the results of a study involving multifluid global simulations including Ohmic dissipation, ambipolar diffusion and the Hall effect in a dynamic, self-consistent way. We focus on the turbulence resulting from the non-linear development of the MRI in radially stratified PPDs and compare with ideal magnetohydrodynamics simulations. In the multifluid simulations, the disc is initially set up to transition from a weak Hall-dominated regime, where the Hall effect is the dominant non-ideal effect but approximately the same as or weaker than the inductive term, to a strong Hall-dominated regime, where the Hall effect dominates the inductive term. As the simulations progress, a substantial portion of the disc develops into a weak Hall-dominated disc. We find a transition from turbulent to laminar flow in the inner regions of the disc, but without any corresponding overall density feature. We introduce a dimensionless parameter, αRM, to characterize accretion with αRM ≳ 0.1 corresponding to turbulent transport. We calculate the eddy turnover time, teddy, and compared this with an effective recombination time-scale, trcb, to determine whether the presence of turbulence necessitates non-equilibrium ionization calculations. We find that trcb is typically around three orders of magnitude smaller than teddy. Also, the ionization fraction does not vary appreciably. These two results suggest that these multifluid simulations should be comparable to single-fluid non-ideal simulations.