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

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 Z(circle dot). 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 similar to 0.5 Myr after disc formation, and then it orbits similar to 200 au from the host star for similar to 0.5 Myr. The protoplanet's mass is similar to 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 similar 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.