16 Cygni Bb

Planetbox begin
name=16 Cygni BbPlanetbox star
star=16 Cygni B
constell=Cygnus
RA=RA|19|41|51.9720
DEC=DEC|+50|31|03.083
dist_ly=70.5
dist_pc=21.6
class=G2.5VbPlanetbox orbit
semimajor=1.681 ± 0.097
eccentricity=0.681 ± 0.017
period=798.5 ± 1.0
long_peri=85.8 ± 2.4
t_peri=2,446,549.1 ± 6.6
semi-amp=50.5 ± 1.6Planetbox character
mass = >1.68 ± 0.15Planetbox discovery
discovery_date = 22 October 1996
discoverers = Cochran "et al."
discovery_method = Radial velocity
discovery_site = flag|United States
discovery_status = Published

16 Cygni 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. It makes one revolution every 799 days and was the first eccentric Jupiter to be discovered.

Discovery

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. 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. [BUTLER P. & MARCY G. , The Lick Observatory Planet Search in: Astronomical and Biochemical Origins and the Search for Life in the Universe, IAU Colloquium No. 161, Capri 1-5 July 1996, eds. C.B. Cosmovici, S. Bowyer, and D. Werthimer]

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. [cite journal|url=http://www.journals.uchicago.edu/doi/abs/10.1086/504701|author=Butler, R. et al.|title=Catalog of Nearby Exoplanets|journal=The Astrophysical Journal|volume=646|pages=505 – 522|year=2006|doi=10.1086/504701 ( [http://exoplanets.org/planets.shtml web version] )] 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. [cite journal|url=http://www.nature.com/nature/journal/v386/n6622/abs/386254a0.html|author=Holman, M. et al.|title=Chaotic variations in the eccentricity of the planet orbiting 16 Cygni B|journal=Nature|volume=386|pages=254 – 256|year=1997|doi=10.1038/386254a0]

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 in 2001 suggested the orbit of 16 Cygni Bb may be highly inclined with respect to our line of sight (at around 173°). [cite journal |url=http://www.obspm.fr/encycl/papers/mas_caps_final_formated.pdf |author=Han, I. et al.|title=Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions|journal=Astrophysical Journal|volume=548|pages=L57 – L60|year=2001|doi=10.1086/318927] This would mean the object's mass may be around 14 times that of Jupiter, making it a low-mass brown dwarf. However these measurements were later proved useful only for upper limits; [cite journal|url=http://adsabs.harvard.edu/abs/2001A%26A...372..935P|title=Screening the Hipparcos-based astrometric orbits of sub-stellar objects|author=Pourbaix, D. and Arenou, F.|journal=Astronomy and Astrophysics|volume=372|pages=935 – 944|year=2001|doi=10.1051/0004-6361:20010597] .

Physical 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. [cite journal|url=http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=105145 |author=Williams, D., Pollard, D.|title=Earth-like worlds on eccentric orbits: excursions beyond the habitable zone|journal=International Journal of Astrobiology|volume=1|pages=61 – 69|year=2002|doi=10.1017/S1473550402001064]

See also

* List of stars with confirmed extrasolar planets
* HD 80606 b

References

External links

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