KMT-2016-BLG-1107: A New Hollywood-Planet Close/Wide Degeneracy

Abstract

We show that microlensing event KMT-2016-BLG-1107 displays a new type of degeneracy between wide-binary and close-binary Hollywood events in which a giant-star source envelops the planetary caustic. The planetary anomaly takes the form of a smooth, two-day "bump" far out on the falling wing of the light curve, which can be interpreted either as the source completely enveloping a minor-image caustic due to a close companion with mass ratio $q=0.036$, or partially enveloping a major-image caustic due to a wide companion with $q=0.004$. The best estimates of the companion masses are both in the planetary regime ($3.3_{-1.8}^{+3.5}{M}_{\mathrm{jup}}$ and $0.090_{-0.037}^{+0.096}{M}_{\mathrm{jup}}$) but differ by an even larger factor than the mass ratios due to different inferred host masses. We show that the two solutions can be distinguished by high-resolution imaging at first light on next-generation ("30m") telescopes. We provide analytic guidance to understand the conditions under which this new type of degeneracy can appear.

arXiv comment23 pages, 7 figures, accepted for publication in AJ

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