Very Large Telescope observations of Gomez's Hamburger: Insights into a young protoplanet candidate

TL;DR

This study presents direct infrared observations of Gomez's Hamburger, revealing a dense clump that is a promising candidate for a young protoplanet formed via gravitational instability, providing insights into planet formation around A stars.

Contribution

First spatially resolved mid-infrared observations of Gomez's Hamburger's disk, identifying a potential protoplanet candidate consistent with gravitational instability formation.

Findings

Detected a dense clump at 350 AU with reduced emission.

Derived physical properties consistent with a protoplanet.

Supports gravitational instability as a planet formation mechanism.

Abstract

Planets are thought to form in the gas and dust disks around young stars. In particular, it has been proposed that giant planets can form through the gravitational instability of massive extended disks around intermediate-mass stars. However, we still lack direct observations to constrain this mechanism. We have spatially resolved the 8.6 and 11.2 $\mu$m emission of a massive protoplanetary disk seen edge on around an A star, Gomez's Hamburger (GoHam), using VISIR at the Very Large Telescope. A compact region situated at a projected distance of $350\pm50$ AU south of the central star is found to have a reduced emission.This asymmetry is fully consistent with the presence of a cold density structure, or clump, identified in earlier CO observations, and we derive physical characteristics consistent with those observations: a mass of 0.8-11.4 Jupiter masses (for a dust-to-gas mass ratio of 0.01), a radius of about 10$^2$ astronomical units, and a local density of about $10^{7}$ cm$^{-3}$. Based on this evidence, we argue that this clump, which we call GoHam b, is a promising candidate for a young protoplanet formed by gravitational instability that might be representative of the precursors of massive planets observed around A stars, such as HR 8799 or Beta pictoris. More detailed studies at high angular resolution are needed to better constrain the physical properties of this object to confirm this proposal.