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 recently reported detection of candidate Jupiter-mass binary objects (JuMBOs) by the James Webb Space Telescope (JWST) has added another puzzling layer. Here, we demonstrate in direct few-body simulations that JuMBOs could arise from the ejection of two giant planets following a close encounter with a passing star, if the two planets are nearly aligned at closest approach. These ejected JuMBOs typically have an average semimajor 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. A comparative analysis of JuMBO rates and properties with current and forthcoming JWST observations across various environments promises to offer insights into the conditions under which these giant planets formed in protoplanetary disks, thereby imposing constraints on theories of giant planet formation.

太阳系以外行星系统的发现对现有的行星形成理论提出了挑战。行星轨道呈现出各种意想不到的结构，自由漂浮的行星似乎无处不在。最近报道称，詹姆斯·韦伯太空望远镜（JWST）探测到了候选木星质量双星物体（JuMBO），这又增加了一层令人费解的地方。在这里，我们在直接少体模拟中证明，如果两颗行星在最接近处几乎对齐，则 JuMBO 可能是由于两颗巨行星在与一颗路过的恒星近距离相遇后的喷射而产生的。这些喷射出的 JuMBO 通常具有大约三倍于其原始行星系统内轨道间隔的平均半长轴和高偏心率，其特征是超热分布，使它们与最初形成的物质不同。我们估计了典型且人口密集的星团中每个行星系统的 JuMBO 形成率，揭示了显着的环境依赖性。在密集的星团中，对于广阔的行星系统来说，这种形成率可以达到几个百分点。对 JuMBO 速率和特性与当前和即将到来的 JWST 在各种环境中的观测进行比较分析，有望提供对这些巨行星在原行星盘中形成的条件的深入了解，从而对巨行星形成理论施加限制。