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Published February 1, 2019 | Version Published + Submitted
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Spitzer Microlensing of MOA-2016-BLG-231L: A Counter-rotating Brown Dwarf Binary in the Galactic Disk

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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.

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Published - Chung_2019_ApJ_871_179.pdf

Submitted - 1902.03150.pdf

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1902.03150.pdf

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Additional details

Identifiers

Eprint ID
92536
Resolver ID
CaltechAUTHORS:20190130-162010020

Related works

Describes
https://arxiv.org/abs/1902.03150 (URL)

Funding

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

Dates

Created
2019-01-31
Created from EPrint's datestamp field
Updated
2021-11-16
Created from EPrint's last_modified field

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Caltech groups
Infrared Processing and Analysis Center (IPAC)