OGLE-2015-BLG-0196: Ground-based Gravitational Microlens Parallax Confirmed by Space-based Observation

January 2017 • 2017ApJ...834...82H

Authors • Han, C. • Udalski, A. • Gould, A. • Zhu, Wei • and • Szymański, M. K. • Soszyński, I. • Skowron, J. • Mróz, P. • Poleski, R. • Pietrukowicz, P. • Kozłowski, S. • Ulaczyk, K. • Pawlak, M. • OGLE Collaboration • Yee, J. C. • Beichman, C. • Calchi Novati, S. • Carey, S. • Bryden, C. • Fausnaugh, M. • Gaudi, B. S. • Henderson, Calen B. • Shvartzvald, Y. • Wibking, B. • Spitzer Microlensing Team

Abstract • In this paper, we present an analysis of the binary gravitational microlensing event OGLE-2015-BLG-0196. The event lasted for almost a year, and the light curve exhibited significant deviations from the lensing model based on the rectilinear lens-source relative motion, enabling us to measure the microlens parallax. The ground-based microlens parallax is confirmed by the data obtained from space-based microlens observations using the Spitzer telescope. By additionally measuring the angular Einstein radius from the analysis of the resolved caustic crossing, the physical parameters of the lens are determined up to the twofold degeneracy, u0 < 0 and u0 > 0, solutions caused by the well-known “ecliptic” degeneracy. It is found that the binary lens is composed of two M dwarf stars with similar masses, M1 = 0.38 ± 0.04 M (0.50 ± 0.05 M) and M2 = 0.38 ± 0.04 M (0.55 ± 0.06 M), and the distance to the lens is DL = 2.77 ± 0.23 kpc (3.30 ± 0.29 kpc). Here the physical parameters outside and inside the parentheses are for the u0 < 0 and u0 > 0 solutions, respectively.


IPAC Authors


Sebastiano Calchi Novati

Associate Scientist

Sean Carey

Senior Scientist