Eccentric Jupiter

An eccentric Jupiter is a Jovian planet that orbits its star in an eccentric orbit. Eccentric Jupiters may disqualify a planetary system from having Earth-like planets (though not always from having habitable exomoons) in it, because a massive gas giant with an eccentric orbit may eject all Earth mass exoplanets from the habitable zone, if not from the system entirely.

The planets of the solar system, except for Mercury, have orbits with an eccentricity of less than 0.1. However, two-thirds of the exoplanets discovered in 2006 have elliptical orbits with an eccentricity of 0.2 or more. The typical exoplanet with an orbital period greater than five days has a median eccentricity of 0.23. The discovery of this type of exoplanet, together with hot Jupiters, has challenged some widely-held theories about solar system formation.