The 2L1S/1L2S Degeneracy for Two Microlensing Planet Candidates Discovered by the KMTNet Survey in 2017

I. -G. Shin , J. C. Yee , A. Gould , M. T. Penny , I. A. Bond , M. D. Albrow , S. -J. Chung , C. Han , K. -H. Hwang , Y. K. Jung , Y. -H. Ryu , Y. Shvartzvald , S. -M. Cha , D. -J. Kim , H. -W. Kim , S. -L. Kim , C. -U. Lee , D. -J. Lee , Y. Lee , B. -G. Park , R. W. Pogge , F. Abe , R. Barry , D. P. Bennett , A. Bhattacharya , M. Donachie , H. Fujii , A. Fukui , Y. Hirao , Y. Itow , Y. Kamei , Iona Kondo , N. Koshimoto , M. C. A. Li , Y. Matsubara , S. Miyazaki , Y. Muraki , M. Nagakane , C. Ranc , N. J. Rattenbury , Harmon Suematsu , D. J. Sullivan , T. Sumi , Daisuke Suzuki , P. J. Tristram , T. Yamakawa , A. Yonehara , P. Fouqué (1, 2) , W. Zang

1 CFHT - Canada-France-Hawaii Telescope Corporation
2 IRAP - Institut de recherche en astrophysique et planétologie

We report two microlensing planet candidates discovered by the Korea Microlensing Telescope Network (KMTNet) survey in 2017. However, both events have the 2L1S/1L2S degeneracy, which is an obstacle to claiming the discovery of the planets with certainty unless the degeneracy can be resolved. For KMT-2017-BLG-0962, the degeneracy cannot be resolved. If the 2L1S solution is correct, KMT-2017-BLG-0962 might be produced by a super Jupiter-mass planet orbiting a mid-M-dwarf host star. For KMT-2017-BLG-1119, the light-curve modeling favors the 2L1S solution but higher-resolution observations of the baseline object tend to support the 1L2S interpretation rather than the planetary interpretation. This degeneracy might be resolved by a future measurement of the lens-source relative proper motion. This study shows that the problem of resolving 2L1S/1L2S degeneracy exists over a much wider range of conditions than those considered by the theoretical study of Gaudi (1998).

Keywords: planets and satellites: detection; gravitational lensing: micro; Astrophysics - Earth and Planetary Astrophysics

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]

I. -G. Shin, J. C. Yee, A. Gould, M. T. Penny, I. A. Bond, et al.. The 2L1S/1L2S Degeneracy for Two Microlensing Planet Candidates Discovered by the KMTNet Survey in 2017. The Astronomical Journal, 2019, 158, ⟨10.3847/1538-3881/ab46a5⟩. ⟨insu-03674397⟩