# Evidence for a circumplanetary disk around protoplanet PDS 70 b

## TL;DR

This study provides the first observational evidence of a circumplanetary disk around protoplanet PDS 70 b, indicating a complex environment with accretion and potential thick clouds, based on spectral analysis.

## Contribution

It introduces the first direct spectral evidence for a circumplanetary disk around PDS 70 b, supporting the presence of circumplanetary material influencing the planet's spectrum.

## Key findings

- Circumplanetary disk contributes excess thermal emission at wavelengths > 2.3 μm.
- Inferred accretion rates are consistent with Hα and Brγ observations.
- Planet's properties: temperature 1500-1600 K, mass ~10 M_J, radius ~1.6 R_J.

## Abstract

We present the first observational evidence for a circumplanetary disk around the protoplanet PDS~70~b, based on a new spectrum in the $K$ band acquired with VLT/SINFONI. We tested three hypotheses to explain the spectrum: Atmospheric emission from the planet with either (1) a single value of extinction or (2) variable extinction, and (3) a combined atmospheric and circumplanetary disk model. Goodness-of-fit indicators favour the third option, suggesting circumplanetary material contributing excess thermal emission --- most prominent at $\lambda \gtrsim 2.3 \mu$m. Inferred accretion rates ($\sim 10^{-7.8}$--$10^{-7.3} M_J$ yr$^{-1}$) are compatible with observational constraints based on the H$\alpha$ and Br$\gamma$ lines. For the planet, we derive an effective temperature of 1500--1600 K, surface gravity $\log(g)\sim 4.0$, radius $\sim 1.6 R_J$, mass $\sim 10 M_J$, and possible thick clouds. Models with variable extinction lead to slightly worse fits. However, the amplitude ($\Delta A_V \gtrsim 3$mag) and timescale of variation ($\lesssim$~years) required for the extinction would also suggest circumplanetary material.