KMT-2018-BLG-1743: Planetary Microlensing Event Occurring on Two Source Stars

Abstract

We present the analysis of the microlensing event KMT-2018-BLG-1743. The light curve of the event, with a peak magnification $A_{\mathrm{peak}}\sim 800$, exhibits two anomaly features, one around the peak and the other on the falling side of the light curve. An interpretation with a binary lens and a single source (2L1S) cannot describe the anomalies. By conducting additional modeling that includes an extra lens (3L1S) or an extra source (2L2S) relative to a 2L1S interpretation, we find that 2L2S interpretations with a planetary lens system and a binary source best explain the observed light curve with $\Delta {\chi }^2\sim 188$ and $\sim 91$ over the 2L1S and 3L1S solutions, respectively. Assuming that these $\Delta {\chi }^2$ values are adequate for distinguishing the models, the event is the fourth 2L2S event and the second 2L2S planetary event. The 2L2S interpretations are subject to a degeneracy, resulting in two solutions with $s>1.0$ (wide solution) and $s<1.0$ (close solution). The masses of the lens components and the distance to the lens are $(M_{\mathrm{host}}/M_{\odot },M_{\mathrm{planet}}/M_{\mathrm{J}},D_{\mathrm{L}}/\mathrm{kpc})\sim (0.19_{-0.111}^{+0.27},0.25_{-0.14}^{+0.34},6.48_{-1.03}^{+0.94})$ and $\sim (0.42_{-0.25}^{+0.34},1.61_{-0.97}^{+1.30},6.04_{-1.27}^{+0.93})$ according to the wide and close solutions, respectively. The source is a binary composed of an early G dwarf and a mid M dwarf. The values of the relative lens-source proper motion expected from the two degenerate solutions, ${\mu }_{\mathrm{wide}}\sim 2.3$mas yr${}^{-1}$ and ${\mu }_{\mathrm{close}}\sim 4.1$mas yr${}^{-1}$, are substantially different, and thus the degeneracy can be broken by resolving the lens and source from future high-resolution imaging observations.

arXiv comment11 pages, 13 figures

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