The imprint of photoevaporation on edge-on discs

TL;DR

This study models how photoevaporation affects dust distribution and morphology in edge-on protoplanetary discs, revealing observable signatures and implications for disc evolution and crystallinity.

Contribution

It introduces detailed hydrodynamic and radiative transfer simulations of dust entrainment in photoevaporative winds around Herbig Ae/Be stars, highlighting morphological and compositional effects.

Findings

Dust grain size distribution varies with radius and height.

The dust morphology exhibits a 'wingnut' shape in images.

Photoevaporative winds can increase crystalline dust fraction.

Abstract

We have performed hydrodynamic and radiative transfer calculations of a photoevaporating disc around a Herbig Ae/Be star to determine the evolution and observational impact of dust entrained in the wind. We find that the wind selectively entrains grains of different sizes at different radii resulting in a dust population that varies spatially and increases with height above the disc at radii > 10 AU. This variable grain population results in a 'wingnut' morphology to the dust density distribution. We calculate images of this dust distribution at NIR wavelengths that also show a wingnut morphology at all wavelengths considered. We have also considered the contribution that crystalline dust grains will have in the wind and show that a photoevaporative wind can result in a significant crystallinity fraction at all radii, when the disc is edge-on. However, when the disc's photosphere is unobscured, a photoevaporative wind makes no contribution to the observable crystallinity fraction in the disc. Finally, we conclude that the analysis of extended emission around edge-on discs could provide a new and independent method of testing photoevaporation models.