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Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb

Han, Cheongho and Shvartzvald, Yossi (2019) Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb. Astronomical Journal, 158 (3). Art. No. 102. ISSN 1538-3881.

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We report the discovery of the microlensing planet OGLE-2018-BLG-0740Lb. The planet is detected with a very strong signal of Δχ^2 ~ 4630, but the interpretation of the signal suffers from two types of degeneracies. One type is caused by the previously known close/wide degeneracy, and the other is caused by an ambiguity between two solutions, in which one solution requires the incorporation of finite-source effects, while the other solution is consistent with a point-source interpretation. Although difficult to be firmly resolved based on only the photometric data, the degeneracy is resolved in strong favor of the point-source solution with the additional external information obtained from astrometric and spectroscopic observations. The small astrometric offset between the source and baseline object supports that the blend is the lens and this interpretation is further secured by the consistency of the spectroscopic distance estimate of the blend with the lensing parameters of the point-source solution. The estimated mass of the host is 1.0 ± 0.1 M⊙ and the mass of the planet is 4.5 ± 0.6 M_J (close solution) or 4.8 ± 0.6 M_J (wide solution) and the lens is located at a distance of 3.2 ± 0.5 kpc. The bright nature of the lens, with I ~ 17.1 (V ~ 18.2), combined with its dominance of the observed flux suggest that radial-velocity (RV) follow-up observations of the lens can be done using high-resolution spectrometers mounted on large telescopes, e.g., Very Large Telescope/ESPRESSO, and this can potentially not only measure the period and eccentricity of the planet but also probe for close-in planets. We estimate that the expected RV amplitude would be ~60sin I m s^(-1).

Item Type:Article
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URLURL TypeDescription Paper
Han, Cheongho0000-0002-2641-9964
Shvartzvald, Yossi0000-0003-1525-5041
Additional Information:© 2019 The American Astronomical Society. Received 2019 April 30; revised 2019 June 26; accepted 2019 June 27; published 2019 August 8. Work by C.H. was supported by the grant (2017R1A4A1015178) of National Research Foundation of Korea. Work by A.G. was supported by US NSF grant AST-1516842. Work by I.G.S. and A.G. were supported by JPL grant 1500811. A.G. received support from the European Research Council under the European Union's Seventh Framework Programme (FP 7) ERC grant Agreement No. [321035]. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. S.D. acknowledges Project 11573003 supported by National Science Foundation of China (NSFC). The MOA project is supported by JSPS KAKENHI grant Nos. JSPS24253004, JSPS26247023, JSPS23340064, JSPS15H00781, JP16H06287, and JP17H02871. Y.M. acknowledges the support of the grant JP14002006. D.P.B., A.B., and C.R. were supported by NASA through grant NASA-80NSSC18K0274. The 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. N.J.R. is a Royal Society of New Zealand Rutherford Discovery Fellow. The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to A.U. 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). We acknowledge the spectral fitting done by Yang Huang and Huawei Zhang.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
National Research Foundation of Korea2017R1A4A1015178
European Research Council (ERC)321035
National Natural Science Foundation of China11573003
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
Japan Society for the Promotion of Science (JSPS)JP14002006
NASA Postdoctoral ProgramUNSPECIFIED
National Science Centre (Poland)MAESTRO 2014/14/A/ST9/00121
Subject Keywords:gravitational lensing: micro – planetary systems
Issue or Number:3
Record Number:CaltechAUTHORS:20190809-095849621
Persistent URL:
Official Citation:Cheongho Han et al 2019 AJ 158 102
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97717
Deposited By: Tony Diaz
Deposited On:09 Aug 2019 17:58
Last Modified:03 Oct 2019 21:34

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