Abstract
Context. Planets are formed amidst young circumstellar disks of gas and dust. The latter is traced by thermal radiation, where strong asymmetric clumps have been observed in a handful of cases. These dust traps could be key to understanding 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 to predict 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. Two-dimensional hydro simulations were performed in which 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 axisymmetric 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 that line-of-sight velocities are barely 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 to test against alternative explanations.
Highlights
Planets are formed in circumstellar disks composed of mainly gas and some solid dust components
Pressure bumps are known to promote the formation of large-scale vortices, through to the Rossby wave instability (RWI), which are proposed as a solution to the barriers in planetesimal formation
The present paper aims to characterize the dynamical signatures expected for a single large Rossby eddy forming in the inner rim of a cavity, by the means of hydro simulations
Summary
Planets are formed in circumstellar disks composed of mainly gas and some solid dust components. Pressure bumps are known to promote the formation of large-scale vortices, through to the Rossby wave instability (RWI), which are proposed as a solution to the barriers in planetesimal formation Large vortices both stop the dust drift and harness efficient growth by lowering relative speeds between grains. Asymmetric dust crescents are being observed in thermal radiation of a growing number of targets (Cazzoletti et al 2018; Dong et al 2018; Isella et al 2018; Casassus et al 2019; Pineda et al 2019) as well as in scattered emission (Benisty et al 2018) Those clumps are candidates for large vortices, and there have been attempts to explain their formation as vortexdriven (Regály et al 2012; Birnstiel et al 2013).
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