Kepler-451 (also known as 2MASS J19383260+4603591 and abbreviated to 2M1938+4603) is an eclipsing post-common envelope binary

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravity, gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally calle ...

that comprises two stars, a pulsating

subdwarf B star A B-type subdwarf (sdB) is a kind of subdwarf star with B-type main-sequence star, spectral type B. They differ from the typical subdwarf by being much hotter and brighter. They are situated at the "extreme horizontal branch" of the Hertzsprung� ...

and a small

red dwarf A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...

star. It is located about away in the constellation Cygnus. It has been hypothesized to host one or more

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

Planetary system

Periodic variations in the timing of this system's eclipses were detected in 2015 using data from the

Kepler space telescope The Kepler space telescope is a defunct space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orb ...

. 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.

References

{{Cygnus (constellation) Binary stars M-type main-sequence stars B-type subdwarfs J19383260+4603591 Hypothetical planetary systems Cygnus (constellation)

451 __NOTOC__ Year 451 ( CDLI) was a common year starting on Monday of the Julian calendar. At the time, it was known as the Year of the Consulship of Marcianus and Adelfius (or, less frequently, year 1204 ''Ab urbe condita''). The denomination 4 ...