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Conference Papers Year : 2015

A rocky planet transiting a nearby low-mass star

Zachory K. Berta-Thompson
  • Function : Author
Jonathan Irwin
  • Function : Author
David Charbonneau
Elisabeth R. Newton
  • Function : Author
Jason Dittmann
  • Function : Author
Nicola Astudillo-Defru
Xavier Bonfils
Michael Gillon
  • Function : Author
Emmanuel Jehin
Antony Stark
  • Function : Author
Brian Stalder
  • Function : Author
Francois Bouchy
Xavier Delfosse
Thierry Forveille
Christoph Lovis
  • Function : Author
Michel Mayor
  • Function : Author
Vasco Neves
  • Function : Author
Francesco Pepe
  • Function : Author
Nuno Santos
Stéphane Udry


Results from Kepler indicate that M dwarfs host, on average, at least 1.4 planets between 0.5 and 1.5 Earth radii per star. Yet, the closest small planets known to transit M dwarfs have been too distant to allow Doppler measurements of their masses or spectroscopic studies of their atmospheres. Here, we announce a new planet discovered by the MEarth-South observatory, an Earth-size planet transiting an M dwarf that is only 12 pc away. The density of the planet, determined from radial velocity observations with HARPS, is consistent with an Earth-like rock/iron composition. With an equilibrium temperature of 530K (assuming a Bond albedo of 0.3), this planet is cooler than most other rocky planets with measured densities. Although too hot to be habitable, it is cool enough that it may have retained a substantial atmosphere over its lifetime. Thanks to the star's proximity and its diminutive size of only 1/5th the radius of the Sun, this new world likely provides the first opportunity for our community to spectroscopically examine the atmosphere of a terrestrial exoplanet. We estimate that JWST could secure high signal-to-noise spectra of the planet's atmosphere, both in transmission during transit and in emission at secondary eclipse.
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Dates and versions

insu-03580887 , version 1 (18-02-2022)



Zachory K. Berta-Thompson, Jonathan Irwin, David Charbonneau, Elisabeth R. Newton, Jason Dittmann, et al.. A rocky planet transiting a nearby low-mass star. American Astronomical Society, 2015, à renseigner, Unknown Region. p. 14-29. ⟨insu-03580887⟩
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