东苏勃，北京大学物理学院天文系教授。南京大学天文学学士；美国俄亥俄州立大学天文学博士；2009年获首届NASA Carl Sagan Exoplanet Fellowship资助，在美国普林斯顿高等研究院从事博士后研究；2013年秋入职北京大学。2017年获中国天文学会“黄授书奖”，2020年获“科学探索奖”。 主要研究方向：用微引力透镜法搜寻系外行星和恒星级黑洞，系外行星的统计分布和动力学演化，超新星的爆发机制。Galactic microlensing is the only known method to discover dark objects ranging from isolated stellar-mass black holes (BHs) to low-mass free-floating planets (FFPs). The recent success of interferometric resolution of microlensed images with VLTI opens up a new venue for discovering isolated stellar remnants. I discuss how the VLTI-GRAVITY+ instrument can significantly advance such discoveries, potentially leading to measuring the mass function of isolated stellar-mass BHs. Ground-based surveys have found more than a dozen ultra-short microlensing events, with the intriguing implication that FFPs are a few times more common than planets bound to stars. I will discuss how space-based microlensing observations can advance the discovery and characterization of FFPs.