A Caltech Library Service

Spitzer + VLTI-GRAVITY Measure the Lens Mass of a Nearby Microlensing Event

Zang, Weicheng and Dong, Subo and Gould, Andrew and Calchi Novati, Sebastiano and Chen, Ping and Yang, Hongjing and Li, Shun-Sheng and Mao, Shude and Alton, K. B. and Brimacombe, J. and Carey, Sean and Christie, G. W. and Delplancke-Ströbele, F. and Feliz, Dax L. and Gaudi, B. Scott and Green, J. and Hu, Shaoming and Jayasinghe, T. and Koff, R. A. and Kurtenkov, A. and Mérand, A. and Minev, Milen and Mutel, Robert and Natusch, T. and Roth, Tyler and Shvartzvald, Yossi and Sun, Fengwu and Vanmunster, T. and Zhu, Wei (2020) Spitzer + VLTI-GRAVITY Measure the Lens Mass of a Nearby Microlensing Event. Astrophysical Journal, 897 (2). Art. No. 180. ISSN 1538-4357. doi:10.3847/1538-4357/ab9749.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


We report the lens mass and distance measurements of the nearby microlensing event TCP J05074264+2447555 (Kojima-1). We measure the microlens parallax vector π_E using Spitzer and ground-based light curves with constraints on the direction of lens-source relative proper motion derived from Very Large Telescope Interferometer (VLTI) GRAVITY observations. Combining this π_E determination with the angular Einstein radius θ_E measured by VLTI-GRAVITY observations, we find that the lens is a star with mass M_L = 0.495±0.063 M⊙ at a distance D_L = 429 ± 21 pc. We find that the blended light basically all comes from the lens. The lens-source proper motion is Μ_(rel,hel) = 26.55±0.36 mas yr⁻¹, so with currently available adaptive-optics instruments, the lens and source can be resolved in 2021. This is the first microlensing event whose lens mass is unambiguously measured by interferometry + satellite-parallax observations, which opens a new window for mass measurements of isolated objects such as stellar-mass black holes.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Zang, Weicheng0000-0001-6000-3463
Dong, Subo0000-0002-1027-0990
Calchi Novati, Sebastiano0000-0002-7669-1069
Chen, Ping0000-0003-0853-6427
Yang, Hongjing0000-0003-0626-8465
Li, Shun-Sheng0000-0001-9952-7408
Mao, Shude0000-0001-8317-2788
Carey, Sean0000-0002-0221-6871
Feliz, Dax L.0000-0002-2457-7889
Jayasinghe, T.0000-0002-6244-477X
Mutel, Robert0000-0003-1511-6279
Shvartzvald, Yossi0000-0003-1525-5041
Zhu, Wei0000-0003-4027-4711
Additional Information:© 2020 The American Astronomical Society. Received 2019 November 29; revised 2020 May 18; accepted 2020 May 18; published 2020 July 16. We thank Tianshu Wang, Jennifer Yee, Akihiko Fukui, and Naoki Koshimoto for fruitful discussions. We are grateful to Robin Leadbeater and Paolo Berardi for making their spectroscopic observations available to us during the observing campaign. S.D. and P.C. are supported by the National Key R&D Program of China No. 2019YFA0405100 and Projects 11573003 supported by the National Science Foundation of China (NSFC). W.Z., H.Y., S.-S.L., and S.M. acknowledge support by the National Science Foundation of China (grant No. 11821303 and 11761131004). Work by AG was supported by AST-1516842 and by JPL grant 1500811. A.G. received support from the European Research Council under the European Unions Seventh Framework Programme (FP 7) ERC grant Agreement No. [321035]. This work is based (in part) on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. Work by S.M.Hu. was supported by the Natural Science Foundation of Shandong province (No. JQ201702), and the Young Scholars Program of Shandong University (No. 20820162003). W.Z. was supported by the Beatrice and Vincent Tremaine Fellowship at CITA.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
National Key Research and Development Program of China2019YFA0405100
National Natural Science Foundation of China11573003
National Natural Science Foundation of China11821303
National Natural Science Foundation of China11761131004
European Research Council (ERC)321035
Natural Science Foundation of Shandong ProvinceJQ201702
Shandong University20820162003
Canadian Institute for Theoretical AstrophysicsUNSPECIFIED
Subject Keywords:Gravitational microlensing ; Satellite microlensing parallax ; Stellar masses ; Stellar distance
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Gravitational microlensing (672); Satellite microlensing parallax (2148); Stellar masses (1614); Stellar distance (1595)
Record Number:CaltechAUTHORS:20200716-102627218
Persistent URL:
Official Citation:Weicheng Zang et al 2020 ApJ 897 180
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104403
Deposited By: Tony Diaz
Deposited On:16 Jul 2020 21:15
Last Modified:16 Nov 2021 18:31

Repository Staff Only: item control page