16 Cygni
Encyclopedia
16 Cygni or 16 Cyg is a triple star system approximately 70 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...

s away from Earth in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

 of Cygnus
Cygnus (constellation)
Cygnus is a northern constellation lying on the plane of the Milky Way. Its name is the Latinized Hellenic word for swan. One of the most recognizable constellations of the northern summer and autumn, it features a prominent asterism known as the Northern Cross...

. It consists of two Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

-like yellow dwarf
Yellow dwarf
A G-type main-sequence star , often called a yellow dwarf, is a main-sequence star of spectral type G and luminosity class V. Such a star has about 0.8 to 1.2 solar masses and surface temperature of between 5,300 and 6,000 K., Tables VII, VIII...

 stars, 16 Cygni A and 16 Cygni B, together with a red dwarf
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....

, 16 Cygni C. In 1996 an extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...

 was discovered in an eccentric orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...

 around 16 Cygni B.

Distance

The parallax of the two brightest stars were measured as part of the Hipparcos
Hipparcos
Hipparcos was a scientific mission of the European Space Agency , launched in 1989 and operated between 1989 and 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky...

 astrometry
Astrometry
Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our Galaxy, the Milky...

 mission. This yielded a parallax of 46.25 milliarcseconds for 16 Cygni A and 46.70 milliarcseconds for 16 Cygni B. Since the two components are associated, it is reasonable to assume they lie at the same distance, so the different parallaxes are a result of experimental error (indeed, when the associated parallax errors are taken into account, the ranges of the parallaxes overlap). Using the parallax of the A component, the distance is 21.6 parsec
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....

s. The parallax of the B component corresponds to a distance of 21.4 parsec
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....

s.

Stellar components

16 Cygni is a hierarchal triple system. Stars A and C form a close binary with a projected separation of 73 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

. The orbital elements
Orbital elements
Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are generally considered in classical two-body systems, where a Kepler orbit is used...

 of the A-C binary are currently unknown. At a distance of 860 AU from A is a third component designated 16 Cygni B. The orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...

 of B relative to the A-C pair was determined in 1999 and not updated since (as of June 2007): plausible orbits range in period from 18,200 to 1.3 million years, with a semimajor axis ranging from 877 to 15,180 AU. In addition B orbits between 100 and 160 degrees inclination, that is against the A-C pole such that 90 degrees would be ecliptical.

Both 16 Cygni A and 16 Cygni B are yellow dwarf
Yellow dwarf
A G-type main-sequence star , often called a yellow dwarf, is a main-sequence star of spectral type G and luminosity class V. Such a star has about 0.8 to 1.2 solar masses and surface temperature of between 5,300 and 6,000 K., Tables VII, VIII...

 stars like our Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

. According to data from the Geneva-Copenhagen survey, both stars have masses similar to the Sun. Age estimates for the two stars vary slightly, but 16 Cygni is likely to be much older than our solar system
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

, at around 10,000 million years old. 16 Cygni C is much fainter than either of these stars, and may be a red dwarf
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....

.

Planetary system

In 1996 an extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...

 in an eccentric orbit was announced around the star 16 Cygni B. The planet's orbit takes 798.5 days to complete, with a semimajor axis of 1.68 AU. Like the majority of known extrasolar planets, 16 Cygni Bb
16 Cygni Bb
16 Cygni Bb or 16 Cyg Bb is an extrasolar planet approximately 70 light-years away in the constellation of Cygnus. The planet was discovered orbiting the sun-like star 16 Cygni B, one of two solar-mass components of the triple star system 16 Cygni...

 was detected by measuring the radial velocity
Radial velocity
Radial velocity is the velocity of an object in the direction of the line of sight . In astronomy, radial velocity most commonly refers to the spectroscopic radial velocity...

 of its parent star, which only gives a lower limit on the mass: in this case, about 1.68 times that of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

. "For the 16 Cyg B system, only particles inside of about 0.3 AU remained stable [within a million years of formation], leaving open the possibility of short-period planets". For them, observation rules out any such planet of over a Neptune mass.

There was a METI message sent to the 16 Cygni system. It was transmitted from Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

's largest radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 – 70-meter (230-foot) Eupatoria
Eupatoria
Yevpatoria or Eupatoria is a city in Crimea, Ukraine.-History:The first recorded settlement in the area, called Kerkinitis , was built by Greek colonists around 500 BC...

 Planetary Radar. The message was named Cosmic Call 1, it was sent on May 24, 1999, and it will arrive at 16 Cygni in November 2069.

The 16 Cygni system is within the field of view of the now-operational Kepler Mission
Kepler Mission
The Kepler spacecraft is an American space observatory, the space-based portion of NASA's Kepler Mission to discover Earth-like planets orbiting other stars. The spacecraft is named in honor of the 17th-century German astronomer Johannes Kepler...

 planet-hunter spacecraft.

See also

  • 61 Cygni
    61 Cygni
    61 Cygni,Not to be confused with 16 Cygni, a more distant system containing two G-type stars harboring the gas giant planet 16 Cygni Bb. sometimes called Bessel's Star or Piazzi's Flying Star, is a binary star system in the constellation Cygnus...

  • 30 Arietis
    30 Arietis
    30 Arietis is a 6th magnitude triple star in the constellation Aries. 30 Arietis A and B are separated by 38.1" or about 1500 AU at a distance of 130 light years away. Based on their luminosities nearly twice that of our Sun, both stars are F-type main sequence, meaning both stars are fusing...

  • 83 Leonis
    83 Leonis
    83 Leonis, abbreviated 83 Leo, is a binary star system approximately 58 light-years away in the constellation of Leo . The primary star of the system is a cool orange subgiant star, while the secondary star is an orange dwarf star. The two stars are separated by at least 515 astronomical units...

  • 54 Piscium
    54 Piscium
    54 Piscium is an orange dwarf star approximately 36 light-years away in the constellation of Pisces. In 2002, an extrasolar planet was confirmed to be orbiting the star, and in 2006, a brown dwarf was also discovered orbiting it....

  • HD 20782
    HD 20782
    HD 20782 is a 7th magnitude G-type main sequence star about 117 light-years away in the constellation of Fornax. HD 20782 is a part of a wide binary system with HD 20781, both stars host a planetary system. This is the first known case of planetary systems around both stars, the primary and...

  • HD 80606
  • HD 89744
    HD 89744
    HD 89744 is an F-dwarf star about 130 light years away in the constellation of Ursa Major. In April 2000, a planet was discovered by radial velocity method.- Stellar components :...

  • HD 222582
    HD 222582
    |- style="background-color: #A0B0FF;" colspan="3"| Planet|- bgcolor="#FFFAFA"| HD 222582 b || |- bgcolor="#FFFAFA"| || HD 222582 is a magnitude 7.7 star approximately 137 light-years away in the constellation of Aquarius...

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