$Spitzer$ Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M-dwarf. (arXiv:1905.05873v1 [astro-ph.EP])

$Spitzer$ Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M-dwarf. (arXiv:1905.05873v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Jung_Y/0/1/0/all/0/1">Youn Kil Jung</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gould_A/0/1/0/all/0/1">Andrew Gould</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Udalski_A/0/1/0/all/0/1">Andrzej Udalski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sumi_T/0/1/0/all/0/1">Takahiro Sumi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yee_J/0/1/0/all/0/1">Jennifer C. Yee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shvartzvald_Y/0/1/0/all/0/1">Yossi Shvartzvald</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zang_W/0/1/0/all/0/1">Weicheng Zang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Han_C/0/1/0/all/0/1">Cheongho Han</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Albrow_M/0/1/0/all/0/1">Michael D. Albrow</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chung_S/0/1/0/all/0/1">Sun Ju Chung</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hwang_K/0/1/0/all/0/1">Kyu-Ha Hwang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ryu_Y/0/1/0/all/0/1">Yoon-Hyun Ryu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shin_I/0/1/0/all/0/1">In-Gu Shin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_W/0/1/0/all/0/1">Wei Zhu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cha_S/0/1/0/all/0/1">Sang-Mok Cha</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_D/0/1/0/all/0/1">Dong-Jin Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_H/0/1/0/all/0/1">Hyoun-Woo Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_S/0/1/0/all/0/1">Seung-Lee Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_C/0/1/0/all/0/1">Chung-Uk Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_D/0/1/0/all/0/1">Dong-Joo Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_Y/0/1/0/all/0/1">Yongseok Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Park_B/0/1/0/all/0/1">Byeong-Gon Park</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pogge_R/0/1/0/all/0/1">Richard W. Pogge</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mroz_P/0/1/0/all/0/1">Przemek Mróz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Szymanski_M/0/1/0/all/0/1">Michał K. Szymański</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Skowron_J/0/1/0/all/0/1">Jan Skowron</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Poleski_R/0/1/0/all/0/1">Radek Poleski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Soszynski_I/0/1/0/all/0/1">Igor Soszyński</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pietrukowicz_P/0/1/0/all/0/1">Paweł Pietrukowicz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kozlowski_S/0/1/0/all/0/1">Szymon Kozłowski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ulaczyk_K/0/1/0/all/0/1">Krzystof Ulaczyk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rybicki_K/0/1/0/all/0/1">Krzysztof A. Rybicki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Iwanek_P/0/1/0/all/0/1">Patryk Iwanek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wrona_M/0/1/0/all/0/1">Marcin Wrona</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beichman_C/0/1/0/all/0/1">Charles A. Beichman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bryden_G/0/1/0/all/0/1">Geoffery Bryden</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Novati_S/0/1/0/all/0/1">Sebastiano Calchi Novati</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carey_S/0/1/0/all/0/1">Sean Carey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gaudi_B/0/1/0/all/0/1">B. Scott Gaudi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Henderson_C/0/1/0/all/0/1">Calen B. Henderson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Abe_F/0/1/0/all/0/1">Fumio Abe</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barry_R/0/1/0/all/0/1">Richard Barry</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bennett_D/0/1/0/all/0/1">David P. Bennett</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bond_I/0/1/0/all/0/1">Ian A. Bond</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bhattacharya_A/0/1/0/all/0/1">Aparna Bhattacharya</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Donachie_M/0/1/0/all/0/1">Martin Donachie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fukui_A/0/1/0/all/0/1">Akihiko Fukui</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hirao_Y/0/1/0/all/0/1">Yuki Hirao</a>, et al. (18 additional authors not shown)

We report the discovery of a $Spitzer$ microlensing planet
OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio $q sim
2times10^{-4}$. The planetary signal, which is characterized by a short $(sim
1~{rm day})$ “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 $M_{rm p} = 13.9pm1.6~M_{oplus}$ orbiting
a mid M-dwarf with a mass of $M_{rm h} = 0.23pm0.03~M_{odot}$. 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
$M_{rm p} = 1.2pm0.2~M_{oplus}$ and $M_{rm h} = 0.15pm0.02~M_{odot}$. 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 $D_{rm L} sim 6pm1~{rm kpc}$. Future adaptive optics
observations may decisively resolve the major image/minor image degeneracy.

http://arxiv.org/icons/sfx.gif