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Creators/Authors contains: "Eckart, Andreas"

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  1. Abstract We resolve the multiple images of the binary-lens microlensing event ASASSN-22av using the GRAVITY instrument of the Very Large Telescope Interferometer (VLTI). The light curves show weak binary-lens perturbations, complicating the analysis, but the joint modeling with the VLTI data breaks several degeneracies, arriving at a strongly favored solution. Thanks to precise measurements of the angular Einstein radiusθE= 0.724 ± 0.002 mas and microlens parallax, we determine that the lens system consists of two M dwarfs with masses ofM1= 0.258 ± 0.008MandM2= 0.130 ± 0.007M, a projected separation ofr= 6.83 ± 0.31 au, and a distance ofDL= 2.29 ± 0.08 kpc. The successful VLTI observations of ASASSN-22av open up a new path for studying intermediate-separation (i.e., a few astronomical units) stellar-mass binaries, including those containing dark compact objects such as neutron stars and stellar-mass black holes. 
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    Free, publicly-accessible full text available December 1, 2025