2025AJ....170...75C

We present the analysis of a microlensing event KMT-2022-BLG-0086 of which the overall light curve is not described by a binary-lens single-source (2L1S) model, which suggests the existence of an extra lens or an extra source. We found that the event is best explained by the binary-lens binary-source (2L2S) model, but the 2L2S model is only favored over the triple-lens single-source (3L1S) model by Δχ² ≃ 9. Although the event has noticeable anomalies around the peak of the light curve, they are not enough covered to constrain the angular Einstein radius θ_E, thus we only measure the minimum angular Einstein radius ${\theta }_{{\rm{E}},{\rm{\min }}}$. From the Bayesian analysis, it is found that that the binary lens system is a binary star with masses of $({m}_{1},{m}_{2})=(0.4{6}_{-0.25}^{+0.35}\,{M}_{\odot },0.7{5}_{-0.55}^{+0.67}\,{M}_{\odot })$ at a distance of ${D}_{{\rm{L}}}=5.8{7}_{-1.79}^{+1.21}$ kpc, while the triple lens system is a brown dwarf or a massive giant planet in a low-mass binary-star system with masses of $({m}_{1},{m}_{2},{m}_{3})=(0.4{3}_{-0.35}^{+0.41}\,{M}_{\odot },0.05{6}_{-0.047}^{+0.055}\,{M}_{\odot }$, $20.8{4}_{-17.04}^{+20.20}\,{M}_{{\rm{J}}})$ at a distance of ${D}_{{\rm{L}}}=4.0{6}_{-3.28}^{+1.39}$ kpc, indicating a disk lens system. The 2L2S model yields the relative lens-source proper motion of μ_rel ≥ 4.6 mas yr^–1 that is consistent with the Bayesian result, whereas the 3L1S model yields μ_rel ≥ 18.9 mas yr^–1, which is more than three times larger than that of a typical disk object of ∼6 mas yr^–1 and thus is not consistent with the Bayesian result. This suggests that the event is likely caused by the binary-lens binary-source model.