Dynamical signatures of Rossby vortices in cavity-hosting disks

TL;DR

This paper predicts observable line-of-sight velocity signatures of Rossby vortices in circumstellar disks using hydro-simulations, aiding in the detection of early planet formation sites through velocity mapping.

Contribution

It introduces a novel method to identify Rossby vortices in disks via line-of-sight velocity perturbations, enhancing observational strategies for planet formation studies.

Findings

Velocity signals are weak but potentially detectable with future instruments.

Spiral patterns in velocity maps can distinguish vortices from other features.

Application to HD 142527 illustrates the method's practical potential.

Abstract

Context: Planets are formed amidst young circumstellar disks of gas and dust. The latter is traced by thermal radiation, where strong asymmetric clumps were observed in a handful of cases. These dust traps could be key to understand the early stages of planet formation, when solids grow from micron-size to planetesimals. Aims: Vortices are among the few known asymmetric dust trapping scenarios. The present work aims at predicting their characteristics in a complementary observable. Namely, line-of-sight velocities are well suited to trace the presence of a vortex. Moreover, the dynamics of disks is subject to recent developments. Methods: 2D hydro-simulations were performed where a vortex forms at the edge of a gas depleted region. We derived idealized line-of-sight velocity maps, varying disk temperature and orientation relative to the observer. The signal of interest, as a small perturbation to the dominant axisymetric component in velocity, may be isolated in observational data using a proxy for the dominant quasi-Keplerian velocity. We propose that the velocity curve on the observational major axis be such a proxy. Results: Applying our method to the disk around HD 142527 as a study case, we predict line-of-sight velocities scarcely detectable by currently available facilities, depending on disk temperature. We show that corresponding spirals patterns can also be detected with similar spectral resolutions, which will help discriminating against alternative explanations.