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Two Earth-sized planets orbiting Kepler-20.

Francois Fressin1, Guillermo Torres, Jason F Rowe

  • 1Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA. ffressin@cfa.harvard.edu

Nature
|December 22, 2011
PubMed
Summary
This summary is machine-generated.

Astronomers discovered two new exoplanets, one Earth-sized and another smaller than Earth, orbiting the star Kepler-20. These rocky planets represent significant progress in the search for Earth analogues beyond our solar system.

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Area of Science:

  • Astronomy and Astrophysics
  • Exoplanetary Science

Background:

  • Observational capabilities have advanced the search for Earth analogues.
  • Exoplanet size is determined by transit photometry, measuring starlight decrease.
  • The smallest previously discovered exoplanet has a radius 1.42 times that of Earth.

Purpose of the Study:

  • To report the discovery of two new exoplanets orbiting the star Kepler-20.
  • To characterize the size of these newly discovered exoplanets.
  • To statistically validate the planetary nature of the observed transit signals.

Main Methods:

  • Transit photometry to detect exoplanets.
  • Statistical analysis to differentiate planetary signals from eclipsing binaries.
  • Theoretical modeling to infer planetary composition and atmosphere.

Main Results:

  • Discovery of two exoplanets around Kepler-20: one Earth-sized (1.03 R(⊕)) and one smaller than Earth (0.87 R(⊕)).
  • Statistical analysis confirms the planetary interpretation with high confidence (>3 orders of magnitude).
  • Gravitational influence of the new planets on the star is below current measurement capabilities.

Conclusions:

  • The discovered exoplanets are likely rocky, composed of iron and silicate.
  • The outer exoplanet may possess a substantial water vapor atmosphere.
  • These findings advance the search for potentially habitable Earth-like exoplanets.