Simulations of Protoplanetary Disk Dispersal: Stellar Mass Dependence of the Disk Lifetime

TL;DR

This study uses one-dimensional simulations to explore how protoplanetary disk lifetimes depend on stellar mass, revealing that disk dispersal times vary from about 10 million years for low-mass stars to 2 million years for high-mass stars, mainly driven by photoevaporation.

Contribution

First comprehensive simulation study including viscous accretion, MHD winds, and photoevaporation across a wide stellar mass range.

Findings

Disk dispersal time varies with stellar mass, from 10 Myr to 2 Myr.

Photoevaporation dominates late-stage disk dispersal.

Inner holes form rapidly in high-mass star disks.

Abstract

Recent infrared and submillimeter observations suggest that the protoplanetary disk lifetime depends on the central stellar mass. The disk dispersal is thought to be driven by viscous accretion, magneto-hydrodynamics (MHD) winds, and photoevaporation by the central star. We perform a set of one-dimensional simulations of long-term disk evolution that include all the three processes. We vary the stellar mass in the range of 0.5-7M$_{\odot}$, and study the mass dependence of the disk evolution. We show that a significant fraction of the disk gas is lost by MHD winds in the early stage, but the later disk evolution is mainly governed by photoevaporation. The disk radius decreases as photoevaporation clears out the gas in the outer disk efficiently. The qualitative evolutionary trends of the disk mass are remarkably similar for the wide range of the central stellar mass we consider, and the time evolution of the disk mass can be well fitted by a simple function. The dispersal time is approximately ten million years for low mass stars with weak mass dependence, but gets as short as two million years around a 7M$_{\odot}$ star. In the latter case, a prominent inner hole is formed by the combined effect of accretion and MHD winds within about one million years. The strength of the MHD wind and viscous accretion controls the overall mass-loss rate, but does not alter the dependence of the dispersal timescale on the central stellar mass.