Dispersal of protoplanetary discs: How stellar properties and the local environment determine the pathway of evolution

TL;DR

This study explores how stellar properties and environment influence the evolution and dispersal pathways of protoplanetary discs, highlighting the roles of internal and external photoevaporation in different scenarios.

Contribution

It identifies five distinct dispersal pathways of protoplanetary discs and analyzes how various parameters affect their evolution and lifetime.

Findings

Five dispersal pathways identified, including inside-out and outside-in dispersal.

Outer disc lifetime is shorter in high UV environments, affecting transition disc prevalence.

Star formation is necessary to match observed disc fractions over time.

Abstract

We study the evolution and final dispersal of protoplanetary discs that evolve under the action of internal and external photoevaporation, and different degrees of viscous transport. We identify five distinct dispersal pathways, which are i) very long lived discs ($>20\,$Myr), ii) inside-out dispersal where internal photoevaporation dominates and opens inner holes, iii) outside-in dispersal where external photoevaporation dominates through disc truncation and two intermediate regimes characterised by lingering material in the inner disc with the outer disc dispersed predominantly by either internal or external photoevaporation. We determine how the lifetime, relative impact of internal and external winds and clearing pathway varies over a wide, plausible, parameter space of stellar/disc/radiation properties. There are a number of implications, for example in high UV environments because the outer disc lifetime is shorter than the time-scale for clearing the inner disc we do not expect transition discs to be common, which appears to be reflected in the location of transition disc populations towards the Orion Nebular Cluster. Irrespective of environment, we find that ongoing star formation is required to reproduce observed disc fractions as a function of stellar cluster age. This work demonstrates the importance of including both internal and external winds for understanding protoplanetary disc evolution.