16 CYGNI BB

'16 Cygni Bb' is an extrasolar planet orbiting the sun-like star 16 Cygni B, one of two solar-mass components of the triple star system 16 Cygni. It makes one revolution every 799 days and was the first eccentric Jupiter to be discovered.

Contents

Discovery

Orbit and mass

Characteristics

See also

References

External links

Discovery

In 1996 the discovery of a planetary-mass companion to the star 16 Cygni B was announced,^[1] with a mass at least 1.68 times that of Jupiter. 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. Like all planets discovered using this method, only a lower limit on the mass is known.

Orbit and mass

Unlike the planets in our 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.^[2] 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.^[3]
The lower limit for the object's mass is well below the dividing line between planets and brown dwarfs at 13 Jupiter masses. Preliminary astrometric measurements, however, suggest the orbit of 16 Cygni Bb may be highly inclined with respect to our line of sight (at around 173°).^[4] This would mean the object's mass may be around 14 times that of Jupiter, making it a low-mass brown dwarf.

Characteristics

Since the planet has only been detected indirectly by measurements of its parent star, properties such as its radius, composition and temperature are unknown.
The planet's highly eccentric orbit means the planet would experience extreme seasonal effects. Despite this, simulations suggest that an Earthlike moon would be able to support liquid water at its surface over the course of a year.^[5]

See also

★ List of stars with confirmed extrasolar planets

★ HD 80606

References

1. The Discovery of a Planetary Companion to 16 Cygni B, Cochran, W. et al., , , Astrophysical Journal, 1997
2. Catalog of Nearby Exoplanets, Butler, R. et al., , , The Astrophysical Journal, 2006 (web version)
3. Chaotic variations in the eccentricity of the planet orbiting 16 Cygni B, Holman, M. et al., , , Nature, 1997
4. Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions, Han, I. et al., , , Astrophysical Journal, 2001
5. Earth-like worlds on eccentric orbits: excursions beyond the habitable zone, Williams, D., Pollard, D., , , International Journal of Astrobiology, 2002

External links

★ 'SIMBAD': 16 Cyg B companion

★ 'Extrasolar Planets Encyclopaedia': Notes for star 16 Cyg B