KMT-2018-BLG-1025Lb: microlensing super-Earth planet orbiting a low-mass
  star
  We aim to find missing microlensing planets hidden in the unanalyzed lensing
events of previous survey data. For this purpose, we conduct a systematic
inspection of high-magnification microlensing events, with peak magnifications
$A_{\rm peak}\gtrsim 30$, in the data collected from high-cadence surveys in
and before the 2018 season. From this investigation, we identify an anomaly in
the lensing light curve of the event KMT-2018-BLG-1025. The analysis of the
light curve indicates that the anomaly is caused by a very low mass-ratio
companion to the lens. We identify three degenerate solutions, in which the
ambiguity between a pair of solutions (solutions B) is caused by the previously
known close--wide degeneracy, and the degeneracy between these and the other
solution (solution A) is a new type that has not been reported before. The
estimated mass ratio between the planet and host is $q\sim 0.8\times 10^{-4}$
for the solution A and $q\sim 1.6\times 10^{-4}$ for the solutions B. From the
Bayesian analysis conducted with measured observables, we estimate that the
masses of the planet and host and the distance to the lens are $(M_{\rm p},
M_{\rm h}, D_{\rm L})\sim (6.1~M_\oplus, 0.22~M_\odot, 6.7~{\rm kpc})$ for the
solution A and $\sim (4.4~M_\oplus, 0.08~M_\odot, 7.5~{\rm kpc})$ for the
solutions B. The planet mass is in the category of a super-Earth regardless of
the solutions, making the planet the eleventh super-Earth planet, with masses
lying between those of Earth and the Solar system's ice giants, discovered by
microlensing.
