What we thought were three confirmed exoplanets have just been knocked off their perch – and a fourth one is under serious doubt.
of MIT, who led the study."Twice [the size of] Jupiter is already suspicious. Larger than that cannot be a planet.", searched for exoplanets by looking for transits. This is when an exoplanet passes between us and its host star, causing regular faint dips in starlight. This creates a 'transit curve' in the star's light that allows scientists to infer the size of the exoplanet.
As our instruments and techniques have improved, scientists have started using something called a phase curve to study exoplanets. This incorporates light from the star that the exoplanet reflects as it orbits, giving more information about the orbiting body.Initially, Niraula and team were studying phase curves to look for exoplanets that have been stretched into a football shape by the gravitational interaction with the host star.
A project called Gaia is changing how we understand the Milky Way. Using stellar parallax, Gaia is mapping the precise position and the motion of Milky Way stars in three-dimensional space with the highest accuracy yet. In 2016, when Kepler-854b was discovered, the Gaia data for its host star weren't available.
However, they are now; when Niraula and colleagues revisited the properties of the exoplanet with revised Gaia data, they found the exoplanet was much larger than first thought, around 3 times the size of Jupiter. They also calculated its mass, around 239 times that of Jupiter; the upper limit for a planet mass is around