K2-291b: A Rocky Super-Earth in a 2.2 day Orbit

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Issue Date
2019-02-13Author
Kosiarek, Molly R.
Blunt, Sarah
López-Morales, Mercedes
Crossfield, Ian
Sinukoff, Evan
Petigura, Erik A.
Gonzales, Erica J.
Poretti, Ennio
Malavolta, Luca
Howard, Andrew W.
Isaacson, Howard
Haywood, Raphaëlle D.
Ciardi, David R.
Bristow, Makennah
Cameron, Andrew Collier
Charbonneau, David
Dressing, Courtney D.
Figueira, Pedro
Fulton, Benjamin J.
Hardee, Bronwen J.
Hirsch, Lea A.
Latham, David W.
Mortier, Annelies
Nava, Chantanelle
Schlieder, Joshua E.
Vanderburg, Andrew
Weiss, Lauren
Bonomo, Aldo S.
Bouchy, François
Buchhave, Lars A.
Coffinet, Adrien
Damasso, Mario
Dumusque, Xavier
Lovis, Christophe
Mayor, Michel
Micela, Giusi
Molinari, Emilio
Pepe, Francesco
Phillips, David
Piotto, Giampaolo
Rice, Ken
Sasselov, Dimitar
Ségransan, Damien
Sozzetti, Alessandro
Udry, Stéphane
Watson, Chris
Publisher
IOP Publishing
Type
Article
Article Version
Scholarly/refereed, publisher version
Rights
© 2019. The American Astronomical Society. All rights reserved.
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Show full item recordAbstract
K2-291 is a solar-type star with a radius of R * = 0.899 ± 0.034 R ⊙ and mass of M* = 0.934 ± 0.038 M ⊙. From the K2 C13 data, we found one super-Earth planet (R p = ${1.589}_{-0.072}^{+0.095}$ R ⊕) transiting this star on a short period orbit (P = ${2.225177}_{-6.8{\rm{e}}\mbox{--}5}^{+6.6{\rm{e}}\mbox{--}5}$ 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 ⊕. 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 ρ = 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.
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Citation
Molly R. Kosiarek et al 2019 AJ 157 116
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