# Scattered light shadows in warped protoplanetary discs

## TL;DR

This study uses 3D hydrodynamic simulations to explore how a misaligned planet can warp a protoplanetary disc, casting observable shadows and brightness variations, with implications for interpreting observations like those of TW Hya.

## Contribution

It demonstrates the impact of a small inclined planet on disc structure and observable shadows, providing a link between planet-induced warps and scattered light images.

## Key findings

- A planet of ~6 Jupiter masses and 2° inclination can cast a significant shadow.
- Warped outer discs cause azimuthal brightness variations at large radii.
- The model suggests inner disc precession alone may not explain TW Hya's features.

## Abstract

Three-dimensional hydrodynamic numerical simulations have demonstrated that the structure of a protoplanetary disc may be strongly affected by a planet orbiting in a plane that is misaligned to the disc. When the planet is able to open a gap, the disc is separated into an inner, precessing disc and an outer disc with a warp. In this work, we compute infrared scattered light images to investigate the observational consequences of such an arrangement. We find that an inner disc misaligned by a less than a degree to the outer disc is indeed able to cast a shadow at larger radii. In our simulations a planet of around 6 Jupiter masses inclined by around 2 degrees is enough to warp the disc and cast a shadow with a depth of more than 10% of the average flux at that radius. We also demonstrate that warp in the outer disc can cause a variation in the azimuthal brightness profile at large radii. Importantly, this latter effect is a function of the distance from the star and is most prominent in the outer disc. We apply our model to the TW Hya system, where a misaligned, precessing inner disc has been invoked to explain an recently observed shadow in the outer disc. Consideration of the observational constraints suggest that an inner disc precessing due to a misaligned planet is an unlikely explanation for the features found in TW Hya.