Gas giants and icy planets

PLATO will address the following questions regarding gas and ice planets:

  • Up to which orbital distance do we find inflated gas giant planets?
  • How does this correlate with stellar parameters (e.g. stellar abundances, type, activity, age)?
  • Are gas giants with massive cores frequent and how does their distribution depend on orbital distance and stellar type?
  • How do gas giants with massive cores form?

How do planetary parameters depend on orbital distances, stellar type, metallicity, chemical composition or age?



Illustration of the interior structure of HD149026b and HD209458b in comparison to Jupiter and Saturn (from Charbonneau et al. 2007).


PLATO will in fact improve our understanding of the composition and evolution of gas giant and Neptune-sized planets in major ways:

  • The planets discovered by PLATO around bright stars will have 3 times more precise radius determinations and 5 times more precise mass determinations than current results. This will allow us to classify detected planets as rocky or icy small planets, or as ice or gas giants, with high accuracy. High precision measurements of planetary radii and masses will allow us to constrain core masses from interior modelling. These can be compared to the largest observed core sizes that failed to undergo gas accretion, and help to constrain planet formation.
  • PLATO will provide the masses and radii of giant planets of various ages. This will allow us to address the contraction history of ice and gas giant planets.
  • PLATO will allow us to address the possibility of compositional change with time, and the connection between age, inflation, and atmospheric loss rate.



PLATO – Revealing habitable worlds around solar-like stars
Definition Study Report, ESA-SCI(2017)1, April 2017