Kepler-451

Kepler-451 (also known as 2MASS J19383260+4603591 and abbreviated to 2M1938+4603) is an eclipsing post-common envelope binary star system that comprises two stars, a pulsating subdwarf B star and a small red dwarf star. It is located about 1340 ly away in the constellation Cygnus. It has been hypothesized to host one or more exoplanets.

Planetary system
Periodic variations in the timing of this system's eclipses were detected in 2015 using data from the Kepler space telescope. It was proposed that these variations are caused by the gravitational effects of a Jupiter-mass planet, Kepler-451b, orbiting with a period of 416 days at a distance of 0.92 AU.

The existence of planets in this system is disputed. An independent study in 2020 found no evidence for Kepler-451b, ruling out the presence of any object of at least Jupiter's mass on the claimed orbit with an inclination greater than 43°. A 2022 study instead proposed a three-planet model, including the originally claimed planet as well as two other planets of similar mass with orbital periods of 43 and 1,800 days.

In general, eclipse timing variations of this type are common in post-common envelope binary systems, and their true cause remains uncertain.