The effect of radiation pressure on the dispersal of photoevaporating discs
Year: 2024
Type: article
Abstract: ABSTRACT Observed infrared (IR) excesses indicate that protoplanetary discs evolve slowly for the majority of their lifetime before losing their near- and mid-IR excesses on short time-scales. Photoevaporation models can explain this ‘two-time-scale’ nature of disc evolution through the removal of inner regions of discs after a few million years. However, they also predict the existence of a population of non-accreting discs with large cavities. Such discs are scarce within the observed population, suggesting the models are incomplete. We explore whether radiation-pressure-driven outflows are able to remove enough dust to fit observations. We simulate these outflows using cudisc, including dust dynamics, growth/fragmentation, radiative transfer and a parametrization of internal photoevaporation. We find that, in most cases, dust mass-loss rates are around 5–10 times too small to meet observational constraints. Particles are launched from the disc inner rim, however grains larger than around a micron do not escape in the outflow, meaning mass-loss rates are too low for the initial dust masses at gap-opening. Only systems that have smooth photoevaporation profiles with gas mass-loss rates $\gt \sim$$5 \times 10^{-9}$$\mathrm{ M}_\odot$ yr$^{-1}$ and disc dust masses $\lt \sim$1 $\mathrm{ M}_{\oplus }$ at the time of gap opening can meet observational constraints; in the current models these manifest as EUV winds driven by atypically large high-energy photon fluxes. We also find that the height of the disc’s photosphere is controlled by small grains in the outflow as opposed to shadowing from a hot inner rim; the effect of this can be seen in synthetic scattered light observations.
Authors: Alfie Robinson, James E Owen, Richard A Booth
Institutions: Imperial College London, University of Leeds
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,012
Awards: G1525616127, G1736745720, G1771230537, G2073976794, G3120427512, G3149743720, The DiRAC 2.5x Facility, G3641108176, G3680780005, G3911511115, G4022262583, G434337789, Planet Evaporation as a Window into Exoplanetary Origins, DiRAC 2.5 Operations 2017-2020, G5660267321, DiRAC 2.5 - the pathway to DiRAC Phase 3, G5997058474, G6181174915, G6537386148, G6802598382, G6955735330, G7108246583, G7447190122, G7536812067, G7573294876, G7629755209, G7702914472, G7937591081, G8150249736, G8695159654, G878803593
OpenAlex ID: W4405222788