Spitzer Microlensing of MOA-2016-BLG-231L: A Counter-rotating Brown Dwarf Binary in the Galactic Disk
Abstract
We analyze the binary microlensing event MOA-2016-BLG-231, which was observed from the ground and from Spitzer. The lens is composed of very-low-mass brown dwarfs (BDs) with M_1 21_(-5)^(+12) M_J and M_2 = 9_(-2)^(+5) M_J, and it is located in the Galactic disk D_L = 2.85_(-0.50)^(+0.88) kpc. This is the fifth binary brown dwarf discovered by microlensing, and the BD binary is moving counter to the orbital motion of disk stars. Constraints on the lens physical properties come from late-time, non-caustic-crossing features of the Spitzer light curve. Thus, MOA-2016-BLG-231 shows how Spitzer plays a crucial role in resolving the nature of BDs in binary BD events with short timescales (≾ 10 days).
Additional Information
© 2019. The American Astronomical Society. Received 2018 July 2; revised 2018 November 12; accepted 2018 December 11; published 2019 January 30. Work by S.-J. Chung was supported by the KASI (Korea Astronomy and Space Science Institute) grant 2018-1-830-02. Work by W.Z. and A.G. was supported by AST-1516842 from the US NSF. W.Z., I.G.S., and A.G. were supported by JPL grant 1500811. Work by C.H. was supported by grant 2017R1A4A1015178 of the National Research Foundation of Korea. Work by C.R. was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by USRA through a contract with NASA. This research has made use of the KMTNet system operated by KASI and the data were obtained at three host sites of CTIO in Chile, SAAO in South Africa, and SSO in Australia. The MOA project is supported by JSPS KAKENHI grants No. JSPS24253004, JSPS26247023, JSPS23340064, JSPS15H00781, JP16H06287, and JP17H02871. The OGLE has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to A.U.Attached Files
Published - Chung_2019_ApJ_871_179.pdf
Submitted - 1902.03150.pdf
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Additional details
- Eprint ID
- 92536
- Resolver ID
- CaltechAUTHORS:20190130-162010020
- Korea Astronomy and Space Science Institute (KASI)
- 2018-1-830-02
- NSF
- AST-1516842
- JPL
- 1500811
- National Research Foundation of Korea
- 2017R1A4A1015178
- NASA Postdoctoral Program
- Japan Society for the Promotion of Science (JSPS)
- JSPS24253004
- Japan Society for the Promotion of Science (JSPS)
- JSPS26247023
- Japan Society for the Promotion of Science (JSPS)
- JSPS23340064
- Japan Society for the Promotion of Science (JSPS)
- JSPS15H00781
- Japan Society for the Promotion of Science (JSPS)
- JP16H06287
- Japan Society for the Promotion of Science (JSPS)
- JP17H02871
- National Science Centre (Poland)
- 2014/14/A/ST9/00121
- Created
-
2019-01-31Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)