Feasibility of interferometric observations and characterization of planet-induced structures at sub au to au scales in protoplanetary disks

TL;DR

This study assesses the potential of interferometric observations, especially with VLTI instruments, to detect and characterize small-scale, planet-induced structures in protoplanetary disks at sub-au to au scales, using simulations.

Contribution

It demonstrates the feasibility of using 3D hydrodynamic and radiative transfer simulations to predict observable signatures of planet-induced disk substructures with current interferometric instruments.

Findings

Detectable variability in visibilities caused by planetary orbital motion.

Substructures similar to observed large-scale features are produced by 300 Earth-mass planets.

Multi-epoch interferometry can differentiate planet-induced features from other variability sources.

Abstract

Interferometric observations of protoplanetary disks by VLTI and ALMA have greatly improved our understanding of the detailed structure of these planetary birthplaces. These observations have revealed a variety of large-scale disk substructures, including rings, gaps, and spirals, spanning tens to hundreds of au, supporting the predictions of planet formation models. Recent instruments, such as MATISSE at the VLTI, allow one to resolve and investigate the inner few au of protoplanetary disks in nearby star formation regions, shedding light on the traces of planet formation and evolution at these small scales. The aim of this work is to assess the feasibility of interferometric observations of small-scale planet-induced substructures in protoplanetary disks in nearby star-forming regions. We aim to characterize these substructures in multi-wavelength and multi-epoch observations and subsequently differentiate between simulation parameters. On the basis of 3D hydrodynamic simulations of embedded planetary companions and subsequent 3D Monte Carlo radiative transfer simulations, we calculated and analyzed interferometric observables, assuming observations with the VLTI in the K, L, M, and N bands. The hydrodynamic simulations exhibit mass-dependent planet-induced density waves that create observable substructures, most notably for the considered case of a 300 $M_{\oplus}$ planet. These substructures share similarities with observed large-scale structures and feature a prominent accretion region around the embedded planet. The visibilities show a detectable variability for multi-epoch VLTI/GRAVITY and VLTI/MATISSE observations, caused by the orbital motion of the planet, that are distinguishable from other sources of variability due to their unique combination of timescale and amplitude.