Microlensing Discovery of a Population of Very Tight, Very Low-mass Binary Brown Dwarfs
J. -Y. Choi, C. Han, A. Udalski, T. Sumi, B. S. Gaudi, A. Gould, D. P. Bennett, M. Dominik, J. -P. Beaulieu, Y. Tsapras, V. Bozza, F. Abe, I. A. Bond, C. S. Bot… 展开作者
J. -Y. Choi, C. Han, A. Udalski, T. Sumi, B. S. Gaudi, A. Gould, D. P. Bennett, M. Dominik, J. -P. Beaulieu, Y. Tsapras, V. Bozza, F. Abe, I. A. Bond, C. S. Botzler, P. Chote, M. Freeman, A. Fukui, K. Furusawa, Y. Itow, C. H. Ling, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, K. Ohnishi, N. J. Rattenbury, To. Saito, D. J. Sullivan, K. Suzuki, W. L. Sweatman, D. Suzuki, S. Takino, P. J. Tristram, K. Wada, P. C. M. Yock, M. K. Szymański, M. Kubiak, G. Pietrzyński, I. Soszyński, J. Skowron, S. Kozłowski, R. Poleski, K. Ulaczyk, Ł. Wyrzykowski, P. Pietrukowicz, L. A. Almeida, D. L. DePoy, Subo Dong, E. Gorbikov, F. Jablonski, C. B. Henderson, K. -H. Hwang, J. Janczak, Y. -K. Jung, S. Kaspi, C. -U. Lee, U. Malamud, D. Maoz, D. McGregor, J. A. Munoz, B. -G. Park, H. Park, R. W. Pogge, Y. Shvartzvald, I. -G. Shin, J. C. Yee, K. A. Alsubai, P. Browne, M. J. Burgdorf, S. Calchi Novati, P. Dodds, X. -S. Fang, F. Finet, M. Glitrup, F. Grundahl, S. -H. Gu, S. Hardis, K. Harpsøe, T. C. Hinse, A. Hornstrup, M. Hundertmark, J. Jessen-Hansen, U. G. Jørgensen, N. Kains, E. Kerins, C. Liebig, M. N. Lund, M. Lundkvist, G. Maier, L. Mancini, M. Mathiasen, M. T. Penny, S. Rahvar, D. Ricci, G. Scarpetta, J. Skottfelt, C. Snodgrass, J. Southworth, J. Surdej, J. Tregloan-Reed, J. Wambsganss, O. Wertz, F. Zimmer, M. D. Albrow, E. Bachelet, V. Batista, S. Brillant, A. Cassan, A. A. Cole, C. Coutures, S. Dieters, D. Dominis Prester, J. Donatowicz, P. Fouqué, J. Greenhill, D. Kubas, J. -B. Marquette, J. W. Menzies, K. C. Sahu, M. Zub, D. M. Bramich, K. Horne, I. A. Steele, R. A. Street
Although many models have been proposed, the physical mechanisms responsible for the formation of low-mass brown dwarfs are poorly understood. The multiplicity properties and minimum mass of the brown-dwarf mass function provide critical empirical diagnostics of these mechanisms. We present the discovery via gravitational microlensing of two very low-mass, very tight binary systems. These binaries have directly and precisely measured total system masses of 0.025 Msun and 0.034 Msun, and projected separations of 0.31 AU and 0.19 AU, making them the lowest-mass and tightest field brown-dwarf binaries known. The discovery of a population of such binaries indicates that brown dwarf binaries can robustly form at least down to masses of ~0.02 Msun. Future microlensing surveys will measure a mass-selected sample of brown-dwarf binary systems, which can then be directly compared to similar samples of stellar binaries.
GAIA卫星可以通过微透镜效应精确测量附近褐矮星和低主序星的质量。如果地面望远镜也能跟踪微透镜事件，提供密集采样的测光，科学产量将最大化。有两种可能的策略。首先，正在发生的事件可以由GAIA的光度或天体测量警报触发。第二，可以用已知的高自行星作为透镜来预测事件。这很容易，因为可以预测事件的位置和时间。使用GAIA源密度，我们估计，高自行（$>300$ mas yr $^{-1}$）棕矮星的样本大小需要提供可预测的事件在5年的任务寿命是令人惊讶的小，只有100的顺序。这与UKIDSS大面积巡天和全天空WISE卫星已经知道的高自行棕矮星的数量相当。如果透镜的相对视差和爱因斯坦半径角可以从天体测量数据中恢复，那么透镜的质量就可以找到。微透镜提供了测量单个物体质量的唯一方法，而不管它们的光度如何。因此，用GAIA进行微透镜是在褐矮星区域进行质量清点的最佳方法。
Revealing Short-period Exoplanets and Brown Dwarfs in the Galactic Bulge using the Microlensing Xallarap Effect with the \textit{Nancy Grace Roman Space Telescope}
\textit{Nancy Grace Roman Space Telescope}（\textit{ Roman}）将提供大量的微透镜光变曲线，其测光精度比正在进行的地面观测高得多。这样的光变曲线将使我们能够观察到以前难以检测的高阶微透镜效应。在本文中，我们研究了\textit{Roman}利用源星的轨道运动，即所谓的xallarap效应，探测和表征源系统中短周期行星和棕矮星（BD）的潜力。我们分析估计xallarap参数的测量不确定度使用Fisher矩阵分析。我们表明，\textit{Roman}银河系外行星巡天（RGES）可以检测到温暖的彗星质量下降到0.5 $M_{\rm Jup}$和轨道周期为30天，通过xallarap效应。假设由\citet{Cumming+2008}得到的行星频率函数，我们发现在微透镜巡天中，\textit{Roman}将探测到$\sim10$热、暖彗星和$\sim30$近距离黑洞。这些探测很可能伴随着对伴星质量和轨道要素的测量，这将有助于研究银河系凸起中近距离行星和BD种群的物理特性。
Candidate Microlensing Brown Dwarfs in Binary Lens Systems from the 2023--2025 Observing Seasons
Chungbuk National University（忠北国立大学）；University of Warsaw（华沙大学）；Massey University（梅西大学）；Korea Astronomy and Space Science Institute（韩国天文学与空间科学研究所）；University of Canterbury（坎特伯雷大学）；Ohio State University（俄亥俄州立大学）；University of Science and Technology（科学技术大学）
Six binary brown dwarf candidates identified by microlensing
Chungbuk National University（忠北国立大学）；Korea Astronomy and Space Science Institute（韩国天文与空间科学研究所）；Massey University（梅西大学）；University of Warsaw（华沙大学）；University of Canterbury（坎特伯雷大学）；Ohio State University（俄亥俄州立大学）；University of Science and Technology（科学技术院）；Weizmann Institute of Science（魏茨曼科学研究所）；Tsinghua University（清华大学）；Kyung Hee University（庆熙大学）；University of Warwick（华威大学）；Villanova University（维拉诺瓦大学）；Nagoya University（名古屋大学）；NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；University of Maryland, College Park（马里兰大学帕克分校）；The University of Tokyo（东京大学）；Osaka University（大阪大学）；The Catholic University of America（美国天主教大学）；Japan Aerospace Exploration Agency（日本宇宙航空研究开发机构）；University of Auckland（奥克兰大学）；Kanto Gakuin University（关东学院大学）；University of Canterbury Mt. John Observatory（坎特伯雷大学约翰山天文台）
KMT-2025-BLG-1314 and KMT-2025-BLG-1392: two microlensing planetary/brown-dwarf candidates analyzed with differentiable code
Tsinghua University（清华大学）；Westlake University（西湖大学）；Korea Astronomy and Space Science Institute（韩国天文与空间科学研究院）；University of Canterbury（坎特伯雷大学）；Max-Planck-Institute for Astronomy（马克斯·普朗克天文学研究所）；Ohio State University（俄亥俄州立大学）；Chungbuk National University（忠北国立大学）；National University of Science and Technology (UST)（韩国科学技术院）
Three New Cool Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer (WISE) and an Improved Spectrum of the Y0 Dwarf WISE J041022.71+150248.4
Four-Body Gravitational Microlensing Events Involving Both a Binary Lens and a Binary Source
Chungbuk National University（忠北国立大学）；Korea Astronomy and Space Science Institute（韩国天文学与空间科学研究院）；Astronomical Observatory, University of Warsaw（华沙大学天文台）；University of Canterbury（坎特伯雷大学）；Ohio State University（俄亥俄州立大学）；University of Science and Technology（科学技术院）
OGLE-2016-BLG-0523: A Low-mass Brown Dwarf or super-Jupiter in a $>100$ au Orbit
Westlake University（西湖大学）；Korea Astronomy and Space Science Institute（韩国天文学与空间科学研究所）；Astronomical Observatory, University of Warsaw（华沙大学天文台）；University of Canterbury（坎特伯雷大学）；Max-Planck-Institute for Astronomy（马克斯·普朗克天体物理学研究所）；Department of Astronomy, Ohio State University（俄亥俄州立大学天文学系）；Department of Physics, Chungbuk National University（忠北国立大学物理系）；National University of Science and Technology (UST)（韩国科学技术院）
A free-floating-planet microlensing event caused by a Saturn-mass object
Department of Astronomy, School of Physics, Peking University（北京大学物理学院天文学系）；Kavli Institute of Astronomy and Astrophysics, Peking University（北京大学科维理天文与天体物理研究所）；Korea Astronomy and Space Science Institute（韩国天文与空间科学研究所）；Astronomical Observatory University of Warsaw（华沙大学天文台）；Department of Particle Physics and Astrophysics, Weizmann Institute of Science（魏茨曼科学研究所粒子物理与天体物理系）；Institute of Astronomy, University of Cambridge（剑桥大学天文研究所）；Department of Astronomy, University of Geneva（日内瓦大学天文学系）；Division of Astrophysics, Department of Physics, Lund University（隆德大学物理系天体物理分部）；Institute for Advanced Study in Physics, Zhejiang University（浙江大学物理学高等研究院）；Institute for Astronomy, School of Physics, Zhejiang University（浙江大学物理学院天体物理研究所）；Department of Astronomy, Tsinghua University（清华大学天文学系）；Max-Planck-Institute for Astronomy（马克斯·普朗克天文学研究所）
