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K2-291b: A rocky super-Earth in a 2.2 day orbit

Research output: Contribution to journalArticle

  • Molly R. Kosiarek
  • Sarah Blunt
  • Mercedes Lopez-Morales
  • Ian J. M. Crossfield
  • Evan Sinukoff
  • Erik A. Petigura
  • Erica J. Gonzales
  • Ennio Poretti
  • Luca Malavolta
  • Andrew W. Howard
  • Howard Isaacson
  • Raphaelle D. Haywood
  • David R. Ciardi
  • Makennah Bristow
  • Andrew Collier Cameron
  • David Charbonneau
  • Courtney D. Dressing
  • Pedro Figueira
  • Benjamin J. Fulton
  • Bronwen J. Hardee
  • Lea A. Hirsch
  • David W. Latham
  • Annelies Mortier
  • Chantanelle Nava
  • Joshua E. Schlieder
  • Andrew Vanderburg
  • Lauren Weiss
  • Aldo S. Bonomo
  • Francois Bouchy
  • Lars A. Buchhave
  • Adrien Coffinet
  • Mario Damasso
  • Xavier Dumusque
  • Christophe Lovis
  • Michel Mayor
  • Giusi Micela
  • Emilio Molinari
  • Francesco Pepe
  • David Phillips
  • Giampaolo Piotto
  • Dimitar Sasselov
  • Damien Segransan
  • Alessandro Sozzetti
  • Stephane Udry
  • Chris Watson

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Original languageEnglish
Number of pages15
JournalAstronomical Journal
Publication statusPublished - 13 Feb 2019


EPIC 247418783 is a solar-type star with a radius of R_star = 0.899 $\pm$ 0.034 R_sun and mass of M_star=0.934 $\pm$ 0.038 M_sun. From K2 C13 data, we found one super-Earth planet (R_p = 1.589+0.095-0.072 R_Earth) transiting this star on a short period orbit (P = 2.225177 +6.6e-5 -6.8e-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 HIRES on Keck I and HARPS-N on Telescopio Nazionale Galileo, we constrained the mass of EPIC 247418783b to M_p = 6.49 $\pm$ 1.16 M_Earth. We found it necessary to model correlated stellar activity radial velocity signals with a Gaussian process in order to more accurately model the effect of stellar noise on our data; the addition of the Gaussian process also improved the precision of this mass measurement. With a bulk density of 8.84+2.50-2.03 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 photo-evaporation during the first billion years of the star's lifetime.

    Research areas

  • astro-ph.EP

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