Spitzer Opens New Path to Break Classic Degeneracy for Jupiter-Mass Microlensing Planet OGLE-2017-BLG-1140Lb (2018)
AuthorsNovati SC, Skowron J, Jung YK, Beichman C, Bryden G, Carey S, Gaudi BS, Henderson CB, Shvartzvald Y, Yee JC, Zhu W, Udalski A, Szymański MK, Mróz P, Poleski R, Soszyński I, Kozłowski S, Pietrukowicz P, Ulaczyk K, Pawlak M, Rybicki K, Iwanek P, Albrow MD, Chung S-J, Gould A, Han C, Hwang K-H, Ryu Y-H, Shin I-G, Zang W, Cha S-M, Kim D-J, Kim H-W, Kim S-L, Lee C-U, Lee D-J, Lee Y, Park B-G, Pogge RWshow all
We analyze the combined Spitzer and ground-based data for OGLE-2017-BLG-1140 and show that the event was generated by a Jupiter-class (m_p\simeq 1.6 M_jup) planet orbiting a mid-late M dwarf (M\simeq 0.2 M_\odot) that lies D_LS\simeq 1.0 kpc in the foreground of the microlensed, Galactic-bar, source star. The planet-host projected separation is a_\perp \simeq 1.0 AU, i.e., well-beyond the snow line. By measuring the source proper motion U_s from ongoing, long-term OGLE imaging, and combining this with the lens-source relative proper motion U_rel derived from the microlensing solution, we show that the lens proper motion U_l=U_rel + U_s is consistent with the lens lying in the Galactic disk. We show that while the Spitzer and ground-based data are comparably well fitted by planetary (i.e., binary-lens, 2L1S) models and by binary-source (1L2S) models, the combination of Spitzer and ground-based data decisively favor the planetary model. This is a new channel to resolve the 2L1S/1L2S degeneracy, which can be difficult to break in some cases.
Keywordsastro-ph.EP; astro-ph.SR; gravitational lensing : micro
ANZSRC Fields of Research02 - Physical Sciences::0201 - Astronomical and Space Sciences::020110 - Stellar Astronomy and Planetary Systems
02 - Physical Sciences::0201 - Astronomical and Space Sciences::020108 - Planetary Science (excl. Extraterrestrial Geology)