Udalski, A.A.UdalskiRyu, Y-HY-HRyuSajadian, S.S.SajadianGould, A.A.GouldMroz, P.P.MrozPoleski, R.R.PoleskiSzymanski, M. K.M. K.SzymanskiSkowron, J.J.SkowronSoszynski, IISoszynskiKozlowski, S.S.KozlowskiPietrukowicz, P.P.PietrukowiczUlaczyk, K.K.UlaczykPawlak, M.M.PawlakRybicki, K.K.RybickiIwanek, P.P.IwanekAlbrow, M. D.M. D.AlbrowChung, S-JS-JChungHan, C.C.HanHwang, K-HK-HHwangJung, Y. K.Y. K.JungShin, I-GI-GShinShvartzvald, Y.Y.ShvartzvaldYee, J. C.J. C.YeeZang, W.W.ZangZhu, W.W.ZhuCha, S-MS-MChaKim, D-JD-JKimKim, H-WH-WKimKim, S-LS-LKimLee, C-UC-ULeeLee, D-JD-JLeeLee, Y.Y.LeePark, B-GB-GParkPogge, R. W.R. W.PoggeBozza, VVBozzaDominik, M.M.DominikHelling, C.C.HellingHundertmark, M.M.HundertmarkJorgensen, U. G.U. G.JorgensenLonga-Pena, P.P.Longa-PenaLowry, S.S.LowryBurgdorf, M.M.BurgdorfCampbell-White, J.J.Campbell-WhiteCiceri, S.S.CiceriEvans, D.D.EvansJaimes, R. FigueraR. FigueraJaimesFujii, Y., IY., IFujiiHaikala, L. K.L. K.HaikalaHenning, T.T.HenningHinse, T. C.T. C.HinseMancini, L.L.ManciniPeixinho, N.N.PeixinhoRahvar, S.S.RahvarRabus, M.M.RabusSkottfelt, J.J.SkottfeltSnodgrass, C.C.SnodgrassSouthworth, J.J.Southworthvon Essen, C.C.von Essen2026-10-192026-10-192018Udalski, A.; Ryu, Y-H; Sajadian, S.; Gould, A.; Mroz, P.; Poleski, R.; Szymanski, M. K.; Skowron, J.; Soszynski, I; Kozlowski, S.; Pietrukowicz, P.; Ulaczyk, K.; Pawlak, M.; Rybicki, K.; Iwanek, P.; Albrow, M. D.; Chung, S-J; Han, C.; Hwang, K-H; Jung, Y. K.; Shin, I-G; Shvartzvald, Y.; Yee, J. C.; Zang, W.; Zhu, W.; Cha, S-M; Kim, D-J; Kim, H-W; Kim, S-L; Lee, C-U; Lee, D-J; Lee, Y.; Park, B-G; Pogge, R. W.; Bozza, V; Dominik, M.; Helling, C.; Hundertmark, M.; Jorgensen, U. G.; Longa-Pena, P.; Lowry, S.; Burgdorf, M.; Campbell-White, J.; Ciceri, S.; Evans, D.; Jaimes, R. Figuera; Fujii, Y., I; Haikala, L. K.; Henning, T.; Hinse, T. C.; Mancini, L.; Peixinho, N.; Rahvar, S.; Rabus, M.; Skottfelt, J.; Snodgrass, C.; Southworth, J.; von Essen, C. (2018). OGLE-2017-BLG-1434Lb: Eighth q < 1 x 10-4 Mass-Ratio Microlens Planet Confirms Turnover in Planet Mass-Ratio Function. ACTA ASTRONOMICA, 68 (1), 1-42. https://doi.org/10.32023/0001-5237/68.1.10001-5237https://hdl.handle.net/20.500.12740/25268We report the discovery of a cold Super-Earth planet (m(p) = 4.4 +/- 0.5 M-circle plus) orbiting a low-mass (M = 0.23 +/- 0.03 M-circle dot) M dwarf at projected separation a(perpendicular to) l = 1.18 +/- 0.10 a.u., i.e., about 1.9 times the distance the snow line. The system is quite nearby for a microlensing planet, D-L = 0.86 +/- 0.09 kpc. Indeed, it was the large lens-source relative parallax pi(rel) = 1.0 mas (combined with the low mass M) that gave rise to the large, and thus well-measured, microlens parallax pi(E) proportional to (pi(rel)/M)(1/2) that enabled these precise measurements. OGLE-2017-BLG-1434Lb is the eighth microlensing planet with planet-host mass ratio q < 1 x 10(-4). We apply a new planet-detection sensitivity method, which is a variant of V/V-max, to seven of these eight planets to derive the mass-ratio function in this regime. We find dN/ d lnq proportional to q(P) , with p =1.05(-0.68)(+0.78), which confirms the turnover in the mass function found by Suzuki et al. relative to the power law of opposite sign n = -0.93 +/- 0.13 at higher mass ratios q greater than or similar to 2 x 10(-4). We combine our result with that of Suzuki et al. to obtain p = 0.73(-0.34)(+0.42.)enGravitational lensing: microPlanetary systemsArticulohttps://doi.org/10.32023/0001-5237/68.1.1