K2-291b : a rocky super-Earth in a 2.2 day orbit
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K2-291 is a solar-type star with a radius of R-* = 0.899 +/- 0.034 R-circle dot and mass of M-* = 0.934 +/- 0.038 M-circle dot. From the K2 C13 data, we found one super-Earth planet (R-p = 1.589(-0.072)(+0.095)R(circle plus)) transiting this star on a short period orbit (P = 2.225177(-6.8e-5)(+6.6e-5) days). We followed this system up with adaptive-optic imaging and spectroscopy to derive stellar parameters, search for stellar companions, and determine a planet mass. From our 75 radial velocity measurements using High Resolution Echelle Spectrometer on Keck I and High Accuracy Radial velocity Planet Searcher in the northern hemisphere on Telescopio Nazionale Galileo, we constrained the mass of K2-291 b to M-p = 6.49 +/- 1.16 M-circle plus. We found it necessary to model correlated stellar activity radial velocity signals with a Gaussian process (GP) in order to more accurately model the effect of stellar noise on our data; the addition of the GP also improved the precision of this mass measurement. With a bulk density of rho = 8.84(-2.03)(+2.50)g cm(-3), the planet is consistent with an Earth-like rock/iron composition and no substantial gaseous envelope. Such an envelope, if it existed in the past, was likely eroded away by photoevaporation during the first billion years of the star's lifetime.
Kosiarek , M R , Blunt , S , Lopez-Morales , M , Crossfield , I J M , Sinukoff , E , Petigura , E A , Gonzales , E J , Poretti , E , Malavolta , L , Howard , A W , Isaacson , H , Haywood , R D , Ciardi , D R , Bristow , M , Cameron , A C , Charbonneau , D , Dressing , C D , Figueird , P , Fulton , B J , Hardee , B J , Hirsch , L A , Latham , D W , Mortier , A , Nava , C , Schlieder , J E , Vanderburg , A , Weiss , L , Bonomo , A S , Bouchy , F , Buchhave , L A , Coffinet , A , Damasso , M , Dumusque , X , Lovis , C , Mayor , M , Micela , G , Molinari , E , Pepe , F , Phillips , D , Piotto , G , Rice , K , Sasselov , D , Segransan , D , Sozzetti , A , Udry , S & Watson , C 2019 , ' K2-291b : a rocky super-Earth in a 2.2 day orbit ' , Astronomical Journal , vol. 157 , no. 3 , 116 . https://doi.org/10.3847/1538-3881/aafe83
Copyright © 2019. The American Astronomical Society. All rights reserved. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at: https://doi.org/10.3847/1538-3881/aafe83
DescriptionA.C.C. acknowledges support from STFC consolidated grant number ST/M001296/1. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant Agreement No. 313014 (ETAEARTH).
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