# Dust traps in the protoplanetary disc MWC 758: two vortices produced by two giant planets?

## TL;DR

This study uses hydrodynamical simulations and radiative transfer calculations to demonstrate that two giant planets in the MWC 758 disc can explain observed dust traps, spirals, and asymmetries.

## Contribution

It introduces a model with two giant planets that reproduces multiple observed features of the MWC 758 protoplanetary disc.

## Key findings

- The outer planet creates a dust-trapping vortex matching ALMA and VLA data.
- The outer planet induces spiral arms similar to observations.
- The inner vortex decays faster, explaining the eccentric ring and dust distribution.

## Abstract

Resolved ALMA and VLA observations indicate the existence of two dust traps in the protoplanetary disc MWC 758. By means of 2D gas+dust hydrodynamical simulations post-processed with 3D dust radiative transfer calculations, we show that the spirals in scattered light, the eccentric, asymmetric ring and the crescent-shaped structure in the (sub)millimetre can all be caused by two giant planets: a 1.5-Jupiter mass planet at 35 au (inside the spirals) and a 5-Jupiter mass planet at 140 au (outside the spirals). The outer planet forms a dust-trapping vortex at the inner edge of its gap (at ~85 au), and the continuum emission of this dust trap reproduces the ALMA and VLA observations well. The outer planet triggers several spiral arms which are similar to those observed in polarised scattered light. The inner planet also forms a vortex at the outer edge of its gap (at ~50 au), but it decays faster than the vortex induced by the outer planet, as a result of the disc's turbulent viscosity. The vortex decay can explain the eccentric inner ring seen with ALMA as well as the low signal and larger azimuthal spread of this dust trap in VLA observations. Finding the thermal and kinematic signatures of both giant planets could verify the proposed scenario.