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OGLE-2014-BLG-1186: gravitational microlensing providing evidence for a planet orbiting the foreground star or for a close binary source?

Dominik, M. and Calchi Novati, S. (2019) OGLE-2014-BLG-1186: gravitational microlensing providing evidence for a planet orbiting the foreground star or for a close binary source? Monthly Notices of the Royal Astronomical Society, 484 (4). pp. 5608-5632. ISSN 0035-8711. doi:10.1093/mnras/stz306.

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Discussing the particularly long gravitational microlensing event OGLE-2014-BLG-1186 with a time-scale t_E ∼ 300 d, we present a methodology for identifying the nature of localised deviations from single-lens point-source light curves, which ensures that (1) the claimed signal is substantially above the noise floor, (2) the inferred properties are robustly determined and their estimation is not subject to confusion with systematic noise in the photometry, (3) alternative viable solutions within the model framework are not missed. Annual parallax and binarity could be separated and robustly measured from the wing and the peak data, respectively. We find matching model light curves that involve either a binary lens or a binary source, and discover hitherto unknown model ambiguities. Our binary-lens models indicate a planet of mass M_2 = (45 ± 9) M⊕, orbiting a star of mass M_1 = (0.35 ± 0.06) M⊙, located at a distance D_L = (1.7 ± 0.3) kpc from Earth, whereas our binary-source models suggest a brown-dwarf lens of M = (0.046 ± 0.007) M⊙, located at a distance D_L = (5.7 ± 0.9) kpc, with the source potentially being a (partially) eclipsing binary involving stars predicted to be of similar colour given the ratios between the luminosities and radii. Further observations might resolve the ambiguity in the interpretation in favour of either a lens or a source binary. We experienced that close binary source stars pose a challenge for claiming the detection of planets by microlensing in events where the source passes very close to the lens star hosting the planet.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Dominik, M.0000-0002-3202-0343
Calchi Novati, S.0000-0002-7669-1069
Additional Information:© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2019 January 24. Received 2019 January 11; in original form 2018 August 8. Published: 29 January 2019. This publication was made possible by grants NPRP-X-019-1-006 and NPRP-09-476-1-78 from the Qatar National Research Fund (a member of Qatar Foundation). GD acknowledges Regione Campania for support from POR-FSE Campania 2014-2020. MPGH acknowledges support from the Villum Foundation. Work by C.H. was supported by the grant (2017R1A4A1015178) of National Research Foundation of Korea. This work makes use of observations from the LCOGT network, which includes three ‘SUPAscopes’ owned by the University of St Andrews. The RoboNet programme is an LCOGT Key Project using time allocations from the University of St Andrews, LCOGT and the University of Heidelberg together with time on the Liverpool Telescope through the Science and Technology Facilities Council (STFC), UK. This research has made use of the LCOGT Archive, which is operated by the California Institute of Technology, under contract with the LCO. OGLE Team thanks Profs. M. Kubiak and G. Pietrzyński, former members of the OGLE team, for their contribution to the collection of the OGLE photometric data over the past years. The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to AU. LM acknowledges support from the Italian Ministry of Instruction, University and Research (MIUR) through FFABR 2017 fund. LM acknowledges support from the University of Rome Tor Vergata through ‘Mission: Sustainability 2016’ fund. KH acknowledges support from STFC grant ST/R000824/1.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Qatar National Research FundNPRP-X-019-1-006
Qatar National Research FundNPRP-09-476-1-78
Regione CampaniaPOR-FSE Campania 2014-2020
Villum FoundationUNSPECIFIED
National Research Foundation of Korea2017R1A4A1015178
National Science Centre (Poland)MAESTRO 2014/14/A/ST9/00121
Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR)FFABR 2017
University of RomeUNSPECIFIED
Science and Technology Facilities Council (STFC)ST/R000824/1
Subject Keywords:gravitational lensing: micro –methods: data analysis –methods: statistical – planets and satellites: detection – (stars:) binaries: eclipsing –Galaxy: kinematics and dynamics
Issue or Number:4
Record Number:CaltechAUTHORS:20190417-104800184
Persistent URL:
Official Citation:M Dominik, E Bachelet, V Bozza, R A Street, C Han, M Hundertmark, A Udalski, D M Bramich, K A Alsubai, S Calchi Novati, S Ciceri, G D’Ago, R Figuera Jaimes, T Haugbølle, T C Hinse, K Horne, U G Jørgensen, D Juncher, N Kains, H Korhonen, L Mancini, J Menzies, A Popovas, M Rabus, S Rahvar, G Scarpetta, R Schmidt, J Skottfelt, C Snodgrass, J Southworth, D Starkey, I A Steele, J Surdej, Y Tsapras, J Wambsganss, O Wertz, P Pietrukowicz, M K Szymański, P Mróz, J Skowron, I Soszyński, K Ulaczyk, R Poleski, Ł Wyrzykowski, S Kozłowski, OGLE-2014-BLG-1186: gravitational microlensing providing evidence for a planet orbiting the foreground star or for a close binary source?, Monthly Notices of the Royal Astronomical Society, Volume 484, Issue 4, April 2019, Pages 5608–5632,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94744
Deposited By: Tony Diaz
Deposited On:17 Apr 2019 21:45
Last Modified:16 Nov 2021 17:07

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