Kepler-16 is an eclipsing

binary star A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...

system in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

of Cygnus that was targeted by the

Kepler Johannes Kepler (27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his laws of p ...

spacecraft. Both stars are smaller than the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

; the primary, Kepler-16A, is a

K-type main-sequence star A K-type main-sequence star, also referred to as a K-type dwarf, or orange dwarf, is a main-sequence (hydrogen-burning) star of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars ...

and the secondary, Kepler-16B, is an M-type

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 ...

. They are separated by 0.23 AU, and complete an orbit around a common center of mass every 41 days. The system is host to one known

extrasolar planet 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 detect ...

in circumbinary orbit: the

Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...

-sized

Kepler-16b Kepler-16b (formally Kepler-16 (AB)-b) is a Saturn-mass exoplanet consisting of half gas and half rock and ice. It orbits a binary star, Kepler-16, with a period of 229 days. " tis the first confirmed, unambiguous example of a circumbinary plan ...

Eclipses

The Kepler-16 system is almost edge-on to Earth and the two stars eclipse each other as they orbit. The larger and brighter primary star is partially eclipsed by the secondary for about six hours and the brightness drops by about 0.15 magnitudes. The secondary star is completely occulted by the primary star for about two hours, but the overall brightness only drops by about 0.02 magnitudes. There are also shallow eclipses caused by a large exoplanet. When this transits across the primary star, the brightness drops by slightly more than the secondary eclipse. When it transits the secondary star, the brightness drops by 0.001 magnitudes.

Planetary system

Kepler-16b is a

gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" was originally synonymous with "giant planet". However, in the 1990s, it became known that Uranu ...

that orbits the two stars in the Kepler-16 system. The planet is a third of Jupiter's mass and slightly smaller than Saturn at 0.7538 Jupiter radii, but is more dense. Kepler-16b completes a nearly circular orbit every 228.776 days.

References

{{Sky, 19, 16, 18.17, +, 51, 45, 26.78 K-type main-sequence stars M-type main-sequence stars Multi-star planetary systems

1611 Events January–March * January 26 – Maximilien de Béthune, Duke of Sully is forced by Queen regent Marie's Regency Council to resign as chief minister of France. He is replaced by Nicolas de Neufville, seigneur de Vill ...

Cygnus (constellation) Eclipsing binaries Planetary systems with one confirmed planet J19161817+5145267