K2-140b and K2-180b - Characterization of a hot Jupiter and a mini-Neptune from the K2 mission

Journal
Date Issued
2019
Author(s)
Korth, J.
•
Csizmadia, Sz
•
Gandolfi, D.
•
Fridlund, M.
•
Pätzold, M.
•
Hirano, T.
•
Livingston, J.
•
Persson, C. M.
•
Deeg, H. J.
•
Justesen, A. B.
•
Barragán, O.
•
Grziwa, S.
•
Endl, M.
•
Tronsgaard, R.
•
Dai, F.
•
Cochran, W. D.
•
Albrecht, S.
•
Alonso, R.
•
Cabrera, J.
•
Cauley, P. W.
•
•
Eigmüller, Ph
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Erikson, A.
•
Esposito, M.
•
Guenther, E. W.
•
Hatzes, A. P.
•
Hidalgo, D.
•
Kuzuhara, M.
•
Montañes, P.
•
•
Narita, N.
•
Niraula, P.
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Nespral, D.
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Nowak, G.
•
Palle, E.
•
Petrillo, C. E.
•
Redfield, S.
•
Prieto-Arranz, J.
•
Rauer, H.
•
Smith, A. M. S.
•
•
Van Eylen, V.
•
Winn, J. N.
DOI
Abstract
We report the independent discovery and characterization of two K2 planets: K2-180b, a mini-Neptune-sized planet in an 8.9-d orbit transiting a V = 12.6 mag, metal-poor ([Fe/H] = -0.65 ± 0.10) K2V star in K2 campaign 5; K2-140b, a transiting hot Jupiter in a 6.6-d orbit around a V = 12.6 mag G6V ([Fe/H] = + 0.10 ± 0.10) star in K2 campaign 10. Our results are based on K2 time-series photometry combined with high-spatial resolution imaging and high-precision radial velocity measurements. We present the first mass measurement of K2-180b. K2-180b has a mass of Mp = 11.3 ± 1.9 M_{\oplus} and a radius of Rp = 2.2 ± 0.1 R_{\oplus}, yielding a mean density of ρp = 5.6 ± 1.9 g cm-3, suggesting a rocky composition. Given its radius, K2-180b is above the region of the so-called `planetary radius gap'. K2-180b is in addition not only one of the densest mini-Neptune-sized planets, but also one of the few mini-Neptune-sized planets known to transit a metal-poor star. We also constrain the planetary and orbital parameters of K2-140b and show that, given the currently available Doppler measurements, the eccentricity is consistent with zero, contrary to the results of a previous study.
Volume
482
Issue
2
Start page
1807
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2019MNRAS.482.1807K
Rights
open.access
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