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Bringing the Visible Universe into Focus with Robo-AO
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Images of a fourth planet orbiting HR 8799.

Christian Marois1, B Zuckerman, Quinn M Konopacky

  • 1National Research Council Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia V9E 2E7, Canada. christian.marois@nrc-cnrc.gc.ca

Nature
|December 15, 2010
PubMed
Summary

Astronomers discovered a fourth giant planet orbiting the star HR 8799. This finding challenges current theories of planet formation, particularly for gas giants forming far from their star.

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Area of Science:

  • Exoplanetary Science
  • Astrophysics
  • Planet Formation

Background:

  • High-contrast near-infrared imaging revealed three giant planets orbiting the star HR 8799.
  • These planets have wide orbits (>25 AU) and are young (<100 Myr), remaining hot and luminous.
  • A key debate in exoplanet science concerns the formation mechanisms of massive outer planets (>10 AU).

Purpose of the Study:

  • To investigate the planet formation theories for the HR 8799 system.
  • To report the discovery of an additional planet within the HR 8799 system.
  • To analyze the implications of the multi-planet system on current formation models.

Main Methods:

  • Utilized high-contrast near-infrared imaging techniques.
  • Analyzed observational data to detect and characterize exoplanets.
  • Compared system architecture with existing planet formation models.

Main Results:

  • A fourth giant planet was detected within the HR 8799 system.
  • This new planet is located interior to the previously known planets and has a similar mass.
  • The system now comprises four young giant planets with wide separations.

Conclusions:

  • The HR 8799 system with four giant planets challenges current planet formation models.
  • In situ formation of all four planets is not adequately explained by existing theories.
  • The system serves as a crucial laboratory for studying giant planet evolution at wide orbital distances.