Authors

And
The Kmtnet Collaboration
The Ogle Collaboration
The Spitzer Team
The Moa Collaboration
The Ukirt Microlensing Team
The Cfht Microlensing Collaboration
Youn Kil Jung, Korea Astronomy and Space Science Institute
Andrew Gould, Korea Astronomy and Space Science Institute
Andrzej Udalski, Uniwersytet Warszawski
Takahiro Sumi, Osaka University
Jennifer C. Yee, Harvard-Smithsonian Center for Astrophysics
Yossi Shvartzvald, Infrared Processing & Analysis Center
Weicheng Zang, Tsinghua University
Cheongho Han, Chungbuk National University
Michael D. Albrow, University of Canterbury
Sun Ju Chung, Korea Astronomy and Space Science Institute
Kyu Ha Hwang, Korea Astronomy and Space Science Institute
Yoon Hyun Ryu, Korea Astronomy and Space Science Institute
In Gu Shin, Korea Astronomy and Space Science Institute
Wei Zhu, L’Institut Canadien d’Astrophysique Théorique
Sang Mok Cha, Korea Astronomy and Space Science Institute
Dong Jin Kim, Korea Astronomy and Space Science Institute
Hyoun Woo Kim, Korea Astronomy and Space Science Institute
Seung Lee Kim, Korea Astronomy and Space Science Institute
Chung Uk Lee, Korea Astronomy and Space Science Institute
Dong Joo Lee, Korea Astronomy and Space Science Institute
Yongseok Lee, Korea Astronomy and Space Science Institute
Byeong Gon Park, Korea Astronomy and Space Science Institute
Richard W. Pogge, The Ohio State University
Przemek Mróz, Uniwersytet Warszawski
Michał K. Szymański, Uniwersytet Warszawski
Jan Skowron, Uniwersytet Warszawski

Document Type

Article

Publication Date

1-1-2019

Abstract

We report the discovery of a Spitzer microlensing planet OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio q ∼ 2 x 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 o. 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 o. 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.

Publication Source (Journal or Book title)

Astronomical Journal

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