Modelling the interplay between protoplanetary disks, planets and X-ray photoevaporative winds: Observational diagnostics

Disk winds and planet-disk interactions are considered to be two of the most important mechanisms that drive the evolution and dispersal of protoplanetary disks and in turn define the environment in which planets form and evolve. While both have been studied extensively in the past, we combine them into one model by performing three-dimensional radiation-hydrodynamic simulations of planet-hosting disks that are undergoing X-ray photoevaporation, with the goal to analyse the interactions between both mechanisms and to produce synthetic observations of common disk and wind diagnostics that could serve as observational tools for testing the interactions between the planet, the disk and the wind in our models.

The models show that a cavity in the gas disk that is carved by a sufficiently massive planet can significantly affect the structure and kinematics of a photoevaporative wind. This effect can be strong enough to be observable in commonly observed wind diagnostic lines, such as the [OI] 6300 Å or [SII] 6730 Å line, which we model with detailed photoionization calculations. When the disk is observed at inclinations around 40° and higher, the synthetic spectral line profiles may exhibit a peak in the redshifted part of the spectrum, which cannot easily be explained by simple wind models alone. Moreover, massive planets can induce asymmetric substructures within the disk and the photoevaporative wind, giving rise to temporal variations of the line profiles that can be strong enough to be observable on timescales of less than a quarter of the planet's orbital period.