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Spitzer Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M Dwarf

Jung, Youn Kil and Shvartzvald, Yossi and Calchi Novati, S. and Henderson, Calen B. and Beichman, Charles A. and Carey, Sean (2019) Spitzer Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M Dwarf. Astronomical Journal, 158 (1). Art. No. 28. ISSN 1538-3881. doi:10.3847/1538-3881/ab237f.

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We report the discovery of a Spitzer microlensing planet OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio q ~ 2 × 10^(−4). The planetary signal, which is characterized by a short (~1 day) "bump" on the rising side of the lensing light curve, was densely covered by ground-based surveys. We find that the signal can be explained by a bright source that fully envelops the planetary caustic, i.e., a "Hollywood" geometry. Combined with the source proper motion measured from Gaia, the Spitzer satellite parallax measurement makes it possible to precisely constrain the lens physical parameters. The preferred solution, in which the planet perturbs the minor image due to lensing by the host, yields a Uranus-mass planet with a mass of M_p = 13.9 ± 1.6 M⊕ orbiting a mid M-dwarf with a mass of M_h = 0.23 ± 0.03 M⊙. There is also a second possible solution that is substantially disfavored but cannot be ruled out, for which the planet perturbs the major image. The latter solution yields M_p = 1.2 ± 0.2 M⊕ and M_h = 0.15 ± 0.02 M⊙. By combining the microlensing and Gaia data together with a Galactic model, we find in either case that the lens lies on the near side of the Galactic bulge at a distance D_L ~ 6 ± 1 kpc. Future adaptive optics observations may decisively resolve the major image/minor image degeneracy.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Jung, Youn Kil0000-0002-0314-6000
Shvartzvald, Yossi0000-0003-1525-5041
Calchi Novati, S.0000-0002-7669-1069
Henderson, Calen B.0000-0001-8877-9060
Beichman, Charles A.0000-0002-5627-5471
Carey, Sean0000-0002-0221-6871
Additional Information:© 2019 The American Astronomical Society. Received 2019 March 27; revised 2019 May 9; accepted 2019 May 20; published 2019 June 21. 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. Work by A.G. was supported by AST-1516842 from the US NSF. A.G. was supported by JPL grant 1500811. A.G. received support from the European Research Council under the European Unions Seventh Framework Programme (FP 7) ERC grant Agreement No. [321035]. Work by C.H. was supported by grant 2017R1A4A1015178 of the National Research Foundation of Korea. Work by M.T.P. was partially supported by NASA grants NNX16AC62G and NNG16PJ32C. The OGLE has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to A.U. The MOA project is supported by JSPS KAKENHI grants No. JSPS24253004, JSPS26247023, JSPS23340064, JSPS15H00781, JP16H06287, and JP17H02871. UKIRT is currently owned by the University of Hawaii (UH) and operated by the UH Institute for Astronomy; operations are enabled through the cooperation of the East Asian Observatory. The collection of the 2018 data reported here was supported by NASA grant NNG16PJ32C and JPL proposal #18-NUP2018-0016. This research uses data obtained through the Telescope Access Program (TAP), which has been funded by the National Astronomical Observatories, Chinese Academy of Sciences, and the Special Fund for Astronomy from the Ministry of Finance. The work by W.Z., T.W., and S.M. is partly supported by the National Science Foundation of China (grant No. 11821303 and 11761131004 to SM).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Research Council (ERC)321035
National Research Foundation of Korea2017R1A4A1015178
National Science Centre (Poland)MAESTRO 2014/14/A/ST9/00121
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 Astronomical Observatories, Chinese Academy of Sciences (NAOC)UNSPECIFIED
Ministry of Finance (China)UNSPECIFIED
National Natural Science Foundation of China11821303
National Natural Science Foundation of China11761131004
Subject Keywords:gravitational lensing: micro – planetary systems
Issue or Number:1
Record Number:CaltechAUTHORS:20190621-105023938
Persistent URL:
Official Citation:Youn Kil Jung et al 2019 AJ 158 28
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96623
Deposited By: Tony Diaz
Deposited On:22 Jun 2019 18:16
Last Modified:16 Nov 2021 17:22

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