OGLE-2017-BLG-1434Lb: eighth q<1×10-4 mass-ratio microlens planet confirms turnover in planet mass-ratio function

We report the discovery of a cold Super-Earth planet - (mp=4.4±0.5 M⊙) orbiting a low-mass - (M=0.23±0.03) 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 w...

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Main Authors: Udalski, Andrzej (Author) , Hundertmark, Markus (Author)
Format: Article (Journal)
Language:English
Published: 2018
In: Acta astronomica
Year: 2018, Volume: 68, Issue: 1, Pages: 1-42
DOI:10.32023/0001-5237/68.1.1
Online Access:Verlag, Volltext: http://acta.astrouw.edu.pl/Vol68/n1/a_68_1_1.html
Verlag, lizenzpflichtig, Volltext: https://doi.org/10.32023/0001-5237/68.1.1
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Author Notes:A. Udalski, Y.-H. Ryu, S. Sajadian, A. Gould and P. Mróz, R. Poleski, M.K. Szymański, J. Skowron, I. Soszyński, S. Kozłowski, P. Pietrukowicz, K. Ulaczyk, M. Pawlak, K. Rybicki, P. Iwanek (OGLE collaboration) M.D. Albrow, S.-J. Chung, C. Han, K.-H. Hwang, Y.K. Jung, I.-G. Shin, Y. Shvartzvald, J.C. Yee, W. Zang, W. Zhu, S.-M. Cha, D.-J. Kim, H.-W. Kim, S.-L. Kim, C.-U. Lee, D.-J. Lee, Y. Lee, B.-G. Park, R.W. Pogge, (KMTNet collaboration) V. Bozza, M. Dominik, C. Helling, M. Hundertmark, U.G. Jørgensen, P. Longa-Peña, S. Lowry, M. Burgdorf, J. Campbell-White, S. Ciceri, D. Evans, R. Figuera Jaimes, Y.I. Fujii, L.K. Haikala, T. Henning, T.C. Hinse, L. Mancini, N. Peixinho, S. Rahvar, M. Rabus, J. Skottfelt, C. Snodgrass, J. Southworth, C. von Essen (MiNDSTEp collaboration)
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Summary:We report the discovery of a cold Super-Earth planet - (mp=4.4±0.5 M⊙) orbiting a low-mass - (M=0.23±0.03) 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<1×10-4. - - 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+0.78-0.68, 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≳2×10-4. We combine our result with - that of Suzuki et al. to obtain p=0.73+0.42-0.34.
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DOI:10.32023/0001-5237/68.1.1