Asteroidscomets

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

February 2020 • 2020JKAS...53....9G

Authors • Gould, Andrew • Ryu, Yoon-Hyun • Calchi Novati, Sebastiano • Zang, Weicheng • Albrow, Michael D. • Chung, Sun-Ju • Han, Cheongho • Hwang, Kyu-Ha • Jung, Youn Kil • Shin, In-Gu • Shvartzvald, Yossi • Yee, Jennifer C. • Cha, Sang-Mok • Kim, Dong-Jin • Kim, Hyoun-Woo • Kim, Seung-Lee • Lee, Chung-Uk • Lee, Dong-Joo • Lee, Yongseok • Park, Byeong-Gon • Pogge, Richard W. • Beichman, Charles • Bryden, Geoff • Carey, Sean • Gaudi, B. Scott • Henderson, Calen B. • Zhu, Wei • Fouque, Pascal • Penny, Matthew T. • Petric, Andreea • Burdullis, Todd • Mao, Shude

Abstract • 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 pi_E measurement. Combined with a measurement of the Einstein radius theta_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_sun and planet M_planet = 7.59 (+0.75, -0.69) M_Earth, system distance D_L = 3.38 (+0.22, -0.26) kpc and projected separation a_perp = 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.

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IPAC Authors
(alphabetical)

Fotina

Sebastiano Calchi Novati

Associate Scientist


Sean Carey

Senior Scientist