16 Cygni Bb
| Exoplanet | List of exoplanets | |
|---|---|---|
| Parent star | ||
| Star | HD 186427 | |
| Constellation | Cygnus | |
| Right ascension | (α) | 19h 41m 51.972s |
| Declination | (δ) | +50° 31′ 03.1″ |
| Distance | 69.2 ± 0.4 ly (21.2 ± 0.1 pc) |
|
| Spectral type | G2.5Vb | |
| Mass | (m) | 0.97 M☉ |
| Radius | (r) | 1.2 R☉ |
| Temperature | (T) | 5752 ± 3.5 K |
| Metallicity | [Fe/H] | 0.09 |
| Age | 9.9 Gyr | |
| Orbital elements | ||
| Semi-major axis | (a) | 1.681 ± 0.097 AU |
| Eccentricity | (e) | 0.689 ± 0.011 |
| Orbital period | (P) | 798.5 ± 1.0 d |
| Inclination | (i) | 45 or 135° |
| Argument of periastron |
(ω) | 83.4 ± 2.1° |
| Time of periastron | (T0) | 2,446,549.1 ± 6.6 JD |
| Semi-amplitude | (K) | 50.5 ± 1.6 m/s |
| Physical characteristics | ||
| Mass | (m) | 2.38 ± 0.04MJ |
| Maximum stellar flux | (F⊙max) | 4.4 ⊕ |
| Minimum stellar flux | (F⊙min) | 0.16 ⊕ |
| Discovery information | ||
| Discovery date | 22 October 1996 | |
| Discoverer(s) | William D. Cochran, Artie P. Hatzes, R. Paul Butler, Geoff Marcy | |
| Discovery method | Radial velocity | |
| Discovery site |
 United States
|
|
| Discovery status | Published | |
| Database references | ||
| Extrasolar Planets Encyclopaedia |
data | |
| SIMBAD | data | |
| Exoplanet Archive | data | |
| Open Exoplanet Catalogue | data | |
16 Cygni Bb or HD 186427 b is an extrasolar planet approximately 69 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 (M☉) components of the triple star system 16 Cygni. It makes one revolution every 799 days and was the first eccentric Jupiter and planet in a triple star system to be discovered.
In October 1996 the discovery of a planetary-mass companion to the star 16 Cygni B was announced, with a mass at least 1.68 times that of Jupiter (MJ). At the time, it had the highest orbital eccentricity of any known extrasolar planet. The discovery was made by measuring the star's radial velocity.
As the inclination of the orbit cannot be directly measured and as no dynamic model of the system was then published, only a lower limit on the mass could then be determined.
Unlike the planets in the Solar System, the planet's orbit is highly elliptical, and its distance varies from 0.54 AU at periastron to 2.8 AU at apastron. This high eccentricity may have been caused by tidal interactions in the binary star system, and the planet's orbit may vary chaotically between low and high-eccentricity states over a period of tens of millions of years.
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