Observable scattered light features from inclined and non-inclined planets embedded in protoplanetary discs

TL;DR

This study uses 3D hydrodynamic and radiative transfer simulations to explore how embedded planets in protoplanetary discs create observable scattered light features, highlighting the importance of vertical disc structure.

Contribution

It presents the first detailed 3D models showing how inclined planets produce distinct scattered light features, emphasizing the significance of vertical disc structure in observations.

Findings

Inclined planets cause shadowing and intensity variations up to 20 times.

Most observable features relate to density variations around 3.3 scale heights.

3D simulations are essential for accurate interpretation of disc features.

Abstract

Over the last few years instruments such as VLT/SPHERE and Subaru/HiCIAO have been able to take detailed scattered light images of protoplanetary discs. Many of the features observed in these discs are generally suspected to be caused by an embedded planet, and understanding the cause of these features requires detailed theoretical models. In this work we investigate disc-planet interactions using the PLUTO code to run 2D and 3D hydrodynamic simulations of protoplanetary discs with embedded 30 M$_{\oplus}$ and 300 M$_{\oplus}$ planets on both an inclined ($i = 2.86^{\circ}$) and non-inclined orbit, using an $\alpha$-viscosity of $4 \times 10^{-3}$. We produce synthetic scattered-light images of these discs at \emph{H-band} wavelengths using the radiative transfer code RADMC3D. We find that while the surface density evolution in 2D and 3D simulations of inclined and non-inclined planets remain fairly similar, their observational appearance is remarkably different. Most of the features seen in the synthetic \emph{H-band} images are connected to density variations of the disc at around 3.3 scale heights above and below the midplane, which emphasizes the need for 3D simulations. Planets on sustained orbital inclinations disrupt the disc's upper-atmosphere and produce radically different observable features and intensity profiles, including shadowing effects and intensity variation in the order of 10-20 times the surrounding background. The vertical optical depth to the disc midplane for \emph{H-band} wavelengths is $\tau \approx 20$ in the disc gap created by the high-mass planet. We conclude that direct imaging of planets embedded in the disc remains difficult to observe, even for massive planets in the gap.