  The discovery of planetary systems beyond our solar system has challenged
established theories of planetary formation. Planetary orbits display a variety
of unexpected architectures, and free-floating planets appear ubiquitous. The
recent detection of candidate Jupiter Mass Binary Objects (JuMBOs) by the James
Webb Space Telescope (JWST) has added another puzzling layer. Here, through
direct few-body simulations, we demonstrate that JuMBOs could arise from the
ejection of double giant planets following a close encounter with a passing
star, if the two planets are nearly aligned at the closest approach. These
ejected JuMBOs typically possess an average semi-major axis approximately three
times the orbital separation within their original planetary system and a high
eccentricity, characterized by a superthermal distribution that sets them apart
from those formed primordially. We estimate the JuMBO formation rate per
planetary system in typical and densely populated clusters, revealing a
significant environmental dependence. In dense clusters, this formation rate
can reach a few percent for wide planetary systems. Comparative analysis of
JuMBO rates and properties with current and forthcoming JWST observations
across various environments promises insights into the conditions under which
these giant planets formed in protoplanetary disks, thereby imposing
constraints on theories of giant planet formation.
