HD 139357 b

HD 139357 b
Exoplanet List of exoplanets
Parent star
Star HD 139357
Constellation Draco
Right ascension (α) 15h 35m 16.20s[1]
Declination (δ) +53° 55′ 19.7″[1]
Apparent magnitude (mV) 5.977
Distance390 ± 10[1] ly
(118 ± 4[1] pc)
Spectral type K4III
Orbital elements
Semi-major axis(a) 2.36 ± 0.2 AU
Periastron (q) 2.12 AU
Apastron (Q) 2.60 AU
Eccentricity (e) 0.1 ± 0.02
Orbital period(P) 1125.7 ± 9 d
(3.0819 ± 0.0246 y)
Argument of
periastron		 (ω) 235.4 ± 10.6°
Time of periastron (T0) 2452466.7 ± 3.2 JD
Physical characteristics
Minimum mass(m sin i)9.76 ± 2.15 MJ
Discovery information
Discovery date March 20, 2009
Discoverer(s) Doellinger et al.[2]
Discovery method radial velocity
Discovery site TLS
Discovery status Published
Other designations
HIP 76311 b, HR 5811 b
Database references
Extrasolar Planets
Encyclopaedia		data
SIMBADdata
Exoplanet Archivedata
Open Exoplanet Cataloguedata

HD 139357 b is a very massive extrasolar planet or brown dwarf located approximately 390 light years away, orbiting the 6th magnitude K-type giant star HD 139357 in the constellation of Draco. The detection occurred on March 20, 2009, which was the first day of spring.

The actual mass and radius of this body remain known, but it has a minimum mass of nearly 10 times that of Jupiter and a radius of probably no more than 1.2 times Jupiter's. Most likely this is a brown dwarf rather than a planet. The reason why the object's true mass is unknown is due to the undetermined inclination of its orbital plane. Follow up observations via direct imaging may determine its radius and orbital inclination, thereby giving its density and surface gravity, which will allow a determination as to whether this object is a brown dwarf or a supermassive planet.

As it is typical for supermassive planets, this orbits further from its host star than Earth is from the Sun. The planet’s year is over three Earth years. However, the orbital eccentricity of this object is much greater than Earth's: 0.1 vs. 0.017. Like most known extrasolar planets, it was detected by the wobble method, which detects planets through the circular wobbling motion of the star caused by the gravity of orbiting body.

See also

References

Coordinates: 15h 35m 16.1992s, +53° 55′ 19.717″


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