Systematic KMTNet Planetary Anomaly Search. II. Six New q < 2 × 10⁻⁴ Mass-ratio Planets

Abstract

Abstract We apply the automated AnomalyFinder algorithm of Paper I to 2018–2019 light curves from the ≃13 deg 2 covered by the six KMTNet prime fields, with cadences Γ ≥ 2 hr −1 . We find a total of 11 planets with mass ratios q &lt; 2 × 10 −4 , including 6 newly discovered planets, 1 planet that was reported in Paper I, and recovery of 4 previously discovered planets. One of the new planets, OGLE-2018-BLG-0977Lb, is in a planetary caustic event, while the other five (OGLE-2018-BLG-0506Lb, OGLE-2018-BLG-0516Lb, OGLE-2019-BLG-1492Lb, KMT-2019-BLG-0253, and KMT-2019-BLG-0953) are revealed by a “dip” in the light curve as the source crosses the host-planet axis on the opposite side of the planet. These subtle signals were missed in previous by-eye searches. The planet-host separations (scaled to the Einstein radius), s , and planet-host mass ratios, q , are, respectively, ( s , q × 10 5 ) = (0.88, 4.1), (0.96 ± 0.10, 8.3), (0.94 ± 0.07, 13), (0.97 ± 0.07, 18), (0.97 ± 0.04, 4.1), and (0.74, 18), where the “ ± ” indicates a discrete degeneracy. The 11 planets are spread out over the range <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>−</mml:mo> <mml:mn>5</mml:mn> <mml:mo>&lt;</mml:mo> <mml:mi>log</mml:mi> <mml:mi>q</mml:mi> <mml:mo>&lt;</mml:mo> <mml:mo>−</mml:mo> <mml:mn>3.7</mml:mn> </mml:math> . Together with the two planets previously reported with q ∼ 10 −5 from the 2018–2019 nonprime KMT fields, this result suggests that planets toward the bottom of this mass-ratio range may be more common than previously believed.