Silva SIRanc CBennett DPBond IAZang WAbe FBarry RBhattacharya AFujii HFukui AHirao YItow YKirikawa RKondo IKoshimoto NMatsubara YMatsumoto SMiyazaki SMuraki YOlmschenk GOkamura ARattenbury NJSatoh YSumi TSuzuki DToda TTristram PJVandorou AYama HPetric ABurdullis TFouqué PMao SPenny MTZhu WRau G2023-11-142023-11-202022-08-312023-11-142023-11-202022-09-01Silva 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. 3.0004-6256https://mro.massey.ac.nz/handle/10179/69197We 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.(c) 2022 The Author/sCC BY 4.0https://creativecommons.org/licenses/by/4.0/Gravitational microlensingGravitational microlensing exoplanet detectionBinary lens microlensing –Exoplanet detection methodsExoplanetsExoplanet systemsExoplanet astronomyJournal article10.3847/1538-3881/ac82b8journal-article118