MOA-2020-BLG-135Lb: A New Neptune-class Planet for the Extended MOA-II Exoplanet Microlens Statistical Analysis

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We report the light-curve analysis for the event MOA-2020-BLG-135, which leads to the discovery of a new Neptune-class planet, MOA-2020-BLG-135Lb. With a derived mass ratio of q = 1.52-0.31+0.39 ´ 10-4 and separation s ≈ 1, the planet lies exactly at the break and likely peak of the exoplanet mass-ratio function derived by the Microlensing Observations in Astrophysics (MOA) Collaboration. We estimate the properties of the lens system based on a Galactic model and considering two different Bayesian priors: one assuming that all stars have an equal planet-hosting probability and the other that planets are more likely to orbit more-massive stars. With a uniform host mass prior, we predict that the lens system is likely to be a planet of mass mplanet = 11.3-6.9+19.2 MÅ and a host star of mass Mhost = 0.23-0.14+0.39 M☉, located at a distance DL = 7.9-1.0+1.0 kpc. With a prior that holds that planet occurrence scales in proportion to the host-star mass, the estimated lens system properties are mplanet = 25-15+22 MÅ, Mhost = 0.53-0.32+0.42 M☉, and DL = 8.3-1.0+0.9 kpc. This planet qualifies for inclusion in the extended MOA-II exoplanet microlens sample.
Gravitational microlensing, Gravitational microlensing exoplanet detection, Binary lens microlensing –, Exoplanet detection methods, Exoplanets, Exoplanet systems, Exoplanet astronomy
Silva SI, Ranc C, Bennett DP, Bond IA, Zang W, Abe F, Barry RK, Bhattacharya A, Fujii H, Fukui A, Hirao Y, Itow Y, Kirikawa R, Kondo I, Koshimoto N, Matsubara Y, Matsumoto S, Miyazaki S, Muraki Y, Olmschenk G, Okamura A, Rattenbury NJ, Satoh Y, Sumi T, Suzuki D, Toda T, Tristram PJ, Vandorou A, Yama H, Petric A, Burdullis T, Fouqué P, Mao S, Penny MT, Zhu W, Rau G. (2022). MOA-2020-BLG-135Lb: A New Neptune-class Planet for the Extended MOA-II Exoplanet Microlens Statistical Analysis. Astronomical Journal. 164. 3.