With a planet–host mass ratio q = 0.012 0.001, KMT-2016-BLG-2605 has the shortest Einstein timescale, t _E = 3.41 0.13 days, of any planetary microlensing event to date. This prompts us to examine the full sample of seven short (t _E < 7 days) planetary events with good q measurements. We find that six have clustered Einstein radii θ _E = 115 20 μas and lens–source relative proper motions μ _rel ≃ 9.5 2.5 mas yr⁻¹. For the seventh, these two quantities could not be measured. These distributions are consistent with a Galactic bulge population of very low mass (VLM) hosts near the hydrogen-burning limit. This conjecture could be verified by imaging at first adaptive optics light on next-generation (30 m) telescopes. Based on a preliminary assessment of the sample, “planetary” companions (i.e., below the deuterium-burning limit) are divided into “genuine planets,” formed in their disks by core accretion, and VLM brown dwarfs, which form like stars. We discuss techniques for expanding the sample, which include taking account of the peculiar “anomaly-dominated” morphology of the KMT-2016-BLG-2605 light curve.

在行星-宿主质量比q = 0.012 0.001 的情况下，KMT-2016-BLG-2605 具有迄今为止所有行星微透镜事件中最短的爱因斯坦时间尺度，t _E = 3.41 0.13 天。这促使我们检查具有良好q测量值的七个短（t _E < 7 天）行星事件的完整样本。我们发现六个聚集了爱因斯坦半径θ _E = 115 20 μ as 和透镜-源相对自身运动μ _rel ≃ 9.5 2.5 mas yr ^-1 . 对于第七个，这两个量无法测量。这些分布与接近氢燃烧极限的极低质量（VLM）宿主的银河凸起群一致。这一猜想可以通过在下一代（30 m）望远镜上对第一批自适应光学光进行成像来验证。根据对样本的初步评估，“行星”伴星（即低于氘燃烧极限）被分为“真正的行星”，通过核心吸积在它们的盘中形成，以及像恒星一样形成的 VLM 褐矮星。我们讨论了扩展样本的技术，其中包括考虑 KMT-2016-BLG-2605 光变曲线特有的“异常主导”形态。