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KMT-2018-BLG-0029Lb: A Very Low Mass-Ratio Spitzer Microlens Planet

Gould, Andrew and Ryu, Yoon-Hyun and Calchi Novati, Sebastiano and Zang, Weicheng and Albrow, Michael D. and Chung, Sun-Ju and Han, Cheongho and Hwang, Kyu-Ha and Jung, Youn Kil and Shin, In-Gu and Shvartzvald, Yossi and Yee, Jennifer C. and Cha, Sang-Mok and Kim, Dong-Jin and Kim, Hyoun-Woo and Kim, Seung-Lee and Lee, Chung-Uk and Lee, Dong-Joo and Lee, Yongseok and Park, Byeong-Gon and Pogge, Richard W. and Beichman, Charles and Bryden, Geoff and Carey, Sean and Gaudi, B. Scott and Henderson, Calen B. and Zhu, Wei and Fouqué, Pascal and Penny, Matthew T. and Petric, Andreea and Burdullis, Todd and Mao, Shude (2020) KMT-2018-BLG-0029Lb: A Very Low Mass-Ratio Spitzer Microlens Planet. Journal of the Korean Astronomical Society, 53 (1). pp. 9-26. ISSN 1225-4614. doi:10.5303/JKAS.2020.53.1.9.

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At q = 1.81 ± 0.20 × 10⁻⁵, KMT-2018-BLG-0029Lb has the lowest planet-host mass ratio q of any microlensing planet to date by more than a factor of two. Hence, it is the first planet that probes below the apparent “pile-up” at q = 5–10 ×10⁻⁵. The event was observed by Spitzer, yielding a microlens-parallax π_E measurement. Combined with a measurement of the Einstein radius θ_E from finite-source effects during the caustic crossings, these measurements imply masses of the host M_(host) = 1.14^(+0.10)_(−0.12)M⊙ and planet M_(planet) = 7.59^(+0.75)_(−0.69)M⊕, system distance D_L = 3.38^(+0.22)_(−0.26) 3.38^(+0.22)_(−0.26) kpc and projected separation a⊥ = 4.27^(+0.21)_(−0.23) 4.27^(+0.21)_(−0.23) AU. The blended light, which is substantially brighter than the microlensed source, is plausibly due to the lens and could be observed at high resolution immediately.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Calchi Novati, Sebastiano0000-0002-7669-1069
Shvartzvald, Yossi0000-0003-1525-5041
Beichman, Charles0000-0002-5627-5471
Carey, Sean0000-0002-0221-6871
Henderson, Calen B.0000-0001-8877-9060
Additional Information:© 2020 Korean Astronomical Society. Published under Creative Commons license CC BY-SA 4.0. Received 27 Jun 2019 Accepted 31 Dec 2019. Print publication date 29 Feb 2020. We thank the anonymous referee for an especially valuable report that helped greatly to clarify the issues presented here. Work by AG was supported by AST-1516842 from the US NSF and by JPL grant 1500811. AG received support from the European Research Council under the European Unions Seventh Framework Programme (FP 7) ERC Grant Agreement n. [321035]. Work by CH was supported by the grant (2017R1A4A1015178) of the National Research Foundation of Korea. 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 are very grateful to the instrumentation and operations teams at CFHT who fixed several failures of MegaCam in the shortest time possible, allowing its return onto the telescope and these crucial observations. WZ and SM acknowledge support by the National Science Foundation of China (Grant No. 11821303 and 11761131004). MTP was supported by NASA grants NNX14AF63G and NNG16PJ32C, as well as the Thomas Jefferson Chair for Discovery and Space Exploration. This research uses data obtained through the Telescope Access Program (TAP), which has been funded by the National Astronomical Observatories of China, the Chinese Academy of Sciences, and the Special Fund for Astronomy from the Ministry of Finance.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Research Council (ERC)321035
National Research Foundation of Korea2017R1A4A1015178
National Natural Science Foundation of China11821303
National Natural Science Foundation of China11761131004
Thomas Jefferson Chair for Discovery and Space ExplorationUNSPECIFIED
National Astronomical Observatories, Chinese Academy of Sciences (NAOC)UNSPECIFIED
Ministry of Finance (China)UNSPECIFIED
Subject Keywords:gravitational microlensing: micro; planetary systems
Issue or Number:1
Record Number:CaltechAUTHORS:20191122-092741946
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100012
Deposited By: Tony Diaz
Deposited On:22 Nov 2019 17:45
Last Modified:16 Nov 2021 17:51

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