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OGLE-2017-BLG-0329L: A Microlensing Binary Characterized with Dramatically Enhanced Precision Using Data from Space-based Observations

Han, C. and Calchi Novati, S. and Beichman, C. and Carey, S. (2018) OGLE-2017-BLG-0329L: A Microlensing Binary Characterized with Dramatically Enhanced Precision Using Data from Space-based Observations. Astrophysical Journal, 859 (2). Art. No. 82. ISSN 1538-4357. doi:10.3847/1538-4357/aabd87.

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Mass measurements of gravitational microlenses require one to determine the microlens parallax π_E, but precise π_E measurement, in many cases, is hampered due to the subtlety of the microlens-parallax signal combined with the difficulty of distinguishing the signal from those induced by other higher-order effects. In this work, we present the analysis of the binary-lens event OGLE-2017-BLG-0329, for which π_E is measured with a dramatically improved precision using additional data from space-based Spitzer observations. We find that while the parallax model based on the ground-based data cannot be distinguished from a zero-π E model at the 2σ level, the addition of the Spitzer data enables us to identify two classes of solutions, each composed of a pair of solutions according to the well-known ecliptic degeneracy. It is found that the space-based data reduce the measurement uncertainties of the north and east components of the microlens-parallax vector π_E by factors ~18 and ~4, respectively. With the measured microlens parallax combined with the angular Einstein radius measured from the resolved caustic crossings, we find that the lens is composed of a binary with component masses of either (M_1, M_2) ~ (1.1, 0.8) M⊙ or ~(0.4, 0.3) M⊙ according to the two solution classes. The first solution is significantly favored but the second cannot be securely ruled out based on the microlensing data alone. However, the degeneracy can be resolved from adaptive optics observations taken ~10 years after the event.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Han, C.0000-0002-2641-9964
Calchi Novati, S.0000-0002-7669-1069
Beichman, C.0000-0002-5627-5471
Carey, S.0000-0002-0221-6871
Additional Information:© 2018 The American Astronomical Society. Received 2018 February 27; revised 2018 April 3; accepted 2018 April 5; published 2018 May 25. Work by C. Han was supported by the grant (2017R1A4A1015178) of the National Research Foundation of Korea. Work by W.Z., Y.K.J., 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. The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to A.U. Work by Y.S. was supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administered by Universities Space Research Association through a contract with NASA. This work was (partially) supported by NASA contract NNG16PJ32C. Work by S.R. and S.S. is supported by INSF-95843339. This research has made use of the KMTNet system operated by the Korea Astronomy and Space Science Institute (KASI) and the data were obtained at three host sites of CTIO in Chile, SAAO in South Africa, and SSO in Australia. We acknowledge the high-speed internet service (KREONET) provided by Korea Institute of Science and Technology Information (KISTI).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
National Research Foundation of Korea2017R1A4A1015178
National Science Centre (Poland)MAESTRO 2014/14/A/ST9/00121
NASA Postdoctoral ProgramUNSPECIFIED
Iran National Science Foundation95843339
Subject Keywords:binaries: general – gravitational lensing: micro
Issue or Number:2
Record Number:CaltechAUTHORS:20180525-091941694
Persistent URL:
Official Citation:C. Han et al 2018 ApJ 859 82
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86618
Deposited By: Tony Diaz
Deposited On:25 May 2018 17:12
Last Modified:15 Nov 2021 20:40

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