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 radius θE = 0.724 ± 0.002 mas and microlens parallax, we determine that the lens system consists of two M dwarfs with masses of M1 = 0.258 ± 0.008 M⊙ and M2 = 0.130 ± 0.007 M⊙, a projected separation of r⊥ = 6.83 ± 0.31 au, and a distance of DL = 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.

中文翻译：

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二元透镜事件的微透镜图像的第一分辨率


我们使用甚大望远镜干涉仪 （VLTI） 的 GRAVITY 仪器解析了双透镜微透镜事件 ASASSN-22av 的多张图像。光曲线显示出微弱的双晶透镜扰动，使分析复杂化，但与 VLTI 数据的联合建模打破了几个简并性，得出了一个非常受欢迎的解决方案。通过精确测量爱因斯坦角半径 θE = 0.724 ± 0.002 mas 和微透镜视差，我们确定透镜系统由两个质量分别为 M1 = 0.258 ± 0.008 M⊙ 和 M2 = 0.130 ± 0.007 M⊙、r⊥ = 6.83 ± 0.31 au 的预计间隔以及 DL = 2.29 ± 0.08 kpc 的距离组成。ASASSN-22av 的成功 VLTI 观测为研究中间分离（即几个天文单位）恒星质量双星开辟了一条新途径，包括那些包含中子星和恒星质量黑洞等暗致密天体的双星。