OGLE-2017-BLG-1434Lb: Eighth q < 1 x 10-4 Mass-Ratio Microlens Planet Confirms Turnover in Planet Mass-Ratio Function
Journal
ACTA ASTRONOMICA
Date Issued
2018
Author(s)
Udalski, 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.
Abstract
We 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.)