OGLE-2017-BLG-1434Lb : eighth q <1 x 10-4 mass-ratio microlens planet confirms turnover in planet mass-ratio function
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We report the discovery of a cold Super-Earth planet (m(p) = 4.4 +/- 0.5 M⊙) orbiting a low-mass (M = 0.23 +/- 0.03 M⊙) M dwarf at projected separation a⊥ = 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, DL = 0.86 ± 0.09 kpc. Indeed, it was the large lens-source relative parallax Πrel = 1.0 mas (combined with the low mass M) that gave rise to the large, and thus well-measured, "microlens parallax" πE ∝ (Πrel/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/Vmax", to seven of these eight planets to derive the mass-ratio function in this regime. We find dN / d lnq ∝ qP , 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).
Udalski , A , Ryu , Y-H , Sajadian , S , Gould , A , Mroz , P , Poleski , R , Szymanski , M K , Skowron , J , Soszynski , 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 , , 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 F , Fujii , Y , 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 , vol. 68 , no. 1 , pp. 1-42 . < https://arxiv.org/abs/1802.02582 >
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DescriptionWork by WZ, YKJ, and AG were supported by AST-1516842 from the US NSF. WZ, IGS, and AG were supported by JPL grant 1500811. Work by C.H. was supported by the grant (2017R1A4A1015178) of National Research Foundation of Korea. This research has made use of the KMTNet system operated by the Korea Astronomy and Space Science Institute (KASI) and the data were obtained at three host sites of CTIO in Chile, SAAO in South Africa, and SSO in Australia. The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to AU. Work by YS was supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, California Institute of Technology, administered by Universities Space Research Association through a contract with NASA.
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