Kapteyn b

Kapteyn b

Exoplanet		List of exoplanets
[[Image:|300px]] Orbit of Kapteyn b
Parent star
Star		Kapteyn's star
Right ascension	(α)	05h 11m 40.58s
Declination	(δ)	+45° 01′ 06.3″
Apparent magnitude	(mV)	8.8
Distance		12.8 ly (3.92±0.01 pc)
Mass	(m)	0.281±0.014 M☉
Radius	(r)	0.291±0.025 R☉
Temperature	(T)	3550±50 K
Metallicity	[Fe/H]	-0.89
Age		8.0±7.5 Gyr
Physical characteristics
Mass	(m)	4.8+0.9 −1.0 M⊕
Stellar flux	(F⊙)	0.4 ⊕
Orbital elements
Semi-major axis	(a)	0.168+0.006 −0.008 AU
Eccentricity	(e)	0.21+0.11 −0.10
Orbital period	(P)	48.616+0.036 −0.032 d
Discovery information
Discovery date		2014
Discoverer(s)
Discovery method		Radial Velocity
Discovery status		Published refereed article
Other designations
Kapteyn b; HIP 24186 b; 2MASS J05114046-4501051 b; TYC 8078-01749-1 b; IRAS 05100-4502 b; WISE J051146.81-450204.5 b; CPD-44 612 b; SAO 217223 b; GJ 191 b; VZ Pic b; Kapteyn's star b; LHS 29 b; HD 33793 b; CD-45 1841 b
Database references
Extrasolar Planets Encyclopaedia		data
SIMBAD		data
Exoplanet Archive		data
Open Exoplanet Catalogue		data

Kapteyn b is a possible exoplanet that orbits the red dwarf Kapteyn's star, located approximately 12.8 light-years (3.92 pc) from Earth. Kapteyn b is within the estimated habitable zone of its star. It is the closest suspected habitable exoplanet to the Solar System other than Tau Ceti e. However, later research has cast doubt on the existence of Kapteyn b, suggesting the signal is consistent with stellar activity rather than a planet.

Kapteyn b has a mass greater than or equal to 4.8±1 M_⊕ and is 0.168AU from the host star orbiting in 48.61 days with an eccentricity of 0.21±0.1.

The system itself is estimated to be 11.5 billion years old, substantially older than the Solar System.

Discovery

The planet was first discovered by the HARPS spectrometer which is housed at the European Southern Observatory's La Silla Observatory in Chile. Further confirmations of the planetary detection where made at the Keck Observatory in Hawaii and at the PFS Observatory, also in Chile.

Methodology

The method of discovery involved observing and recording tiny wobbles in the star caused by the gravitational tug of its planets, using Doppler spectroscopy.

Additional planet

One other planet has been detected within the same planetary system. It is designated "Kapteyn c" and orbits further out from the star, beyond the outer edge of the habitable zone. It is considered to be too cold for stellar-light based life.

See also

• Habitability of red dwarf systems
• List of potentially habitable exoplanets

External links

• NASA – Kapteyn b at The NASA Exoplanet Archive.
• Kapteyn's b at The Extrasolar Planets Encyclopaedia from the Paris Observatory
• Kapteyn b in the Habitable Exolanets Catalog at UPR-Arecibo.