Kepler-1625 b

Kepler-1625b is a super-Jupiter exoplanet orbiting the Sun-like star Kepler-1625 about away in the constellation of Cygnus. The large gas giant is approximately the same radius as Jupiter, and orbits its star every 287.4 days. In 2017, hints of a Neptune-sized exomoon in orbit of the planet were found using photometric observations collected by the Kepler Mission. Further evidence for a Neptunian moon was found the following year using the Hubble Space Telescope, where two independent lines of evidence constrained the mass and radius to be Neptune-like. The mass-signature has been independently recovered by two other teams. However, the radius-signature was independently recovered by one of the teams but not the other. The original discovery team later showed that this latter study appears affected by systematic error sources that may have influenced its findings.

==Characteristics== ===Mass and radius=== Kepler-1625b is a Jovian-sized gas giant, a type of planet several times greater in radius than Earth and mostly composed of hydrogen and helium. It has been estimated to be 11.4±1.5 times Earth's radius, approximately equal to that of the planet Jupiter. Its mass is unknown, but is constrained at 3-sigma confidence to be less than 11.6 times the mass of Jupiter (about 3,700 Earth masses), based on non-detection in radial velocity observations. This indicates that it is below the deuterium-fusing limit, which is around 13 Jupiter masses, and so it is not a brown dwarf.