TOWARD A GLOBAL EVOLUTIONARY MODEL OF PROTOPLANETARY DISKS

By Xue-Ning Bai. 2016

142 citations recorded by the source corpus.

A global picture of the evolution of protoplanetary disks (PPDs) is key to understanding almost every aspect of planet formation, where standard α-disk models have been continually employed for their simplicity. In the meantime, disk mass loss has been conventionally attributed to photoevaporation, which controls disk dispersal. However, a paradigm shift toward accretion driven by magnetized disk winds has taken place in recent years, thanks to studies of non-ideal magnetohydrodynamic effects in PPDs. I present a framework of global PPD evolution aiming to incorporate these advances, highlighting the role of wind-driven accretion and wind mass loss. Disk evolution is found to be largely dominated by wind-driven processes, and viscous spreading is suppressed. The timescale of disk evolution is controlled primarily by the amount of external magnetic flux threading the disks, and how rapidly the disk loses the flux. Rapid disk dispersal can be achieved if the disk is able to hold most of its magnetic flux during the evolution. In addition, because wind launching requires a sufficient level of ionization at the disk surface (mainly via external far-UV (FUV) radiation), wind kinematics is also affected by the FUV penetration depth and disk geometry. For a typical disk lifetime of a few million years, the disk loses approximately the same amount of mass through the wind as through accretion onto the protostar, and most of the wind mass loss proceeds from the outer disk via a slow wind. Fractional wind mass loss increases with increasing disk lifetime. Significant wind mass loss likely substantially enhances the dust-to-gas mass ratio and promotes planet formation.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/bd39c449bc65bffd1a61df57b8957db34dbb763b

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Citations in the corpus

The Effect of Jupiter's Formation on the Distribution of Refractory Elements and Inclusions in Meteorites (2017, background): “While the magnetorotational instability (MRI) was considered for a long time to be the most likely mechanism for transporting mass and angular momentum in disks, recent work has shown that non-ideal effects suppress the MRI more than had been anticipated, and that other magnetic effects, such as mag”
THE MASS–METALLICITY RELATION FOR GIANT PLANETS (2015, background): “11 g S 3 p 2 These values—displayed in Figure 16 for the same planets plotted in Figure 14—span a reasonable theoretical range for protoplanetary disks, particularly in dead zones, where most giant planets are thought to form (e.g., Turner et al. 2014; Bai 2016).”
Planetesimal formation starts at the snow line (2017, background): “This is motivated by the fact that in many recent protoplanetary disk models the angular momentum transfer is not necessarily driven by turbulence anymore, and even if it is, a quiescent midplane layer is often formed (Dzyurkevich et al. 2013; Turner et al. 2014; Bai 2016).”
Global Simulations of the Inner Regions of Protoplanetary Disks with Comprehensive Disk Microphysics (2017, methodology): “This is consistent with previous local simulations (Bai 2014, 2015), and for a given vertical field, the amplification factor also depends on the assumed grain abundance (e.g., see Lesur et al. 2014; Simon et al. 2015; Xu & Bai 2016 where different grain abundances are adopted).”