* Astronomy

Title: Very Large Telescope observations of Gomez's Hamburger: Insights into a young protoplanet candidate
Author: O. Berne, A. Fuente, E. Pantin, V. Bujarrabal, C. Baruteau, P. Pilleri, E. Habart, F. Menard, J. Cernicharo, A. Tielens, C. Joblin

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 via gravitational instability of massive extended disks around intermediate mass stars. However, direct observations to constrain this mechanism lack. We have spatially resolved the 8.6 and 11.2 µm emission of a massive edge on protoplanetary disk 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±50 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 the order of 10² astronomical units, a local density of the order of 10⁷ 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 could be representative of the precursors of massive planets observed around A stars, like HR 8799. Further studies at high angular resolution are needed to better constrain the physical properties of this object in order to confirm this proposal.

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Position (2000): RA 18 09 13.3, Dec -32 10 48