Formation of a wide-orbit giant planet in a gravitationally unstable subsolar-metallicity protoplanetary disc

Author(s): Ryoki Matsukoba, Eduard I. Vorobyov, Takashi Hosokawa, Manuel Guedel
Abstract: Direct imaging observations of planets revealed that wide-orbit (>10 au) giant planets exist even around subsolar-metallicity host stars and do not require metal-rich environments for their formation. A possible formation mechanism of wide-orbit giant planets in subsolar-metallicity environments is the gravitational fragmentation of massive protoplanetary discs. Here, we follow the long-term evolution of the disc for 1 Myr after its formation, which is comparable to disc lifetime, by way of a two-dimensional thin-disc hydrodynamic simulation with the metallicity of 0.1. We find a giant protoplanet that survives until the end of the simulation. The protoplanet is formed by the merger of two gaseous clumps at ∼0.5 Myr after disc formation, and then it orbits ∼200 au from the host star for ∼0.5 Myr. The protoplanet's mass is ∼10 M_J at birth and gradually decreases to 1 M_J due to the tidal effect from the host star. The result provides the minimum mass of 1 M_J for the protoplanet in our simulation. We anticipate that the mass of a protoplanet experiencing reduced mass loss thanks to the protoplanetary contraction in higher resolution simulations can increase to ∼10 M_J. We argue that the disc gravitational fragmentation would be a promising pathway to form wide-orbit giant planets with masses of ≥1 M_J in subsolar-metallicity environments.
Organisation(s): Department of Astrophysics
External organisation(s): Southern Federal University, Kyoto University
Journal: Monthly Notices of the Royal Astronomical Society
Volume: 526
Pages: 3933-3943
No. of pages: 11
ISSN: 0035-8711
DOI: https://doi.org/10.1093/mnras/stad3003
Publication date: 12-2023
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics, 103038 Space exploration
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/34391396-6f46-4328-a553-88a45a755fbc

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