GJ 1214

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GJ 1214
Morgan-Keenan spectral classification zoom.png

GJ 1214 is a M-class dwarf star
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus[1]
Right ascension 17h 15m 18.942s[2]
Declination +04° 57′ 49.69″[2]
Apparent magnitude (V) 14.71 ± 0.03[3]
Spectral type M4.5[4]
Apparent magnitude (B) 16.40[5]
Apparent magnitude (R) 13.8[5]
Apparent magnitude (I) 11.52 ± 0.03[3]
Apparent magnitude (J) 9.750 ± 0.024[2]
Apparent magnitude (H) 9.094 ± 0.024[2]
Apparent magnitude (K) 8.782 ± 0.020[2]
B−V color index 1.73[6]
V−R color index 0.9
R−I color index 2.7
Variable type planetary transit[7]
Radial velocity (Rv) +21.1 ± 1.0[3] km/s
Proper motion (μ) RA: 585[8] mas/yr
Dec.: -752[8] mas/yr
Parallax (π) 68.71 ± 0.6[9] mas
Distance 47.5 ± 0.4 ly
(14.6 ± 0.1 pc)
Absolute magnitude (MV) 14.10
Mass 0.157 ± 0.019[7] M
Radius 0.2064+0.0086
[3] R
Luminosity 0.00328[7] L
Surface gravity (log g) 4.991 ± 0.029[7] cgs
Temperature 3,026 ± 130[7] K
Metallicity 0.39 ± 0.15[4]
Rotation >25 days[3]
Age Gyr
Other designations
LHS 3275, G 139-21, NLTT 44431, 2MASS J17151894+0457496, LSPM J1715+0457, UBV M 53793, USNO-B1.0 0949-00280047, GEN# +9.80139021.[5]
Database references
Exoplanet Archive data
Extrasolar Planets

GJ 1214 is a dim M4.5[4] red dwarf in the constellation Ophiuchus with an apparent magnitude of 14.7.[3] It is located at a distance of approximately 47 light years from Earth.[9] It is about one-fifth as large as the Sun[10] with a surface temperature estimated to be 3,000 K (2,730 °C; 4,940 °F).[10] Its luminosity is only 0.003% that of the Sun.[10]

The estimate for the stellar radius is 15% larger than predicted by theoretical models.[7] It also shows a 1% intrinsic variability in the near-infrared probably caused by stellar spots.[3]

Planetary system[edit]

In mid-December 2009, a team of Harvard-Smithsonian astronomers announced the discovery of a companion extrasolar planet, GJ 1214 b, potentially composed largely of water and having the mass and diameter of a super-Earth.[7][10]

The GJ 1214 system[3][7]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b 6.55 ± 0.98 M 0.0143 ± 0.0019 1.58040456 ± 1.6x10-7[11] <0.27 88.17° 2.64 ± 0.13 R
The newly discovered super-Earth surrounding the nearby star GJ 1214.
This artist’s impression shows how the newly discovered super-Earth orbiting the nearby star GJ 1214 may look. Credit: ESO/L. Calçada

Discovered by the MEarth project and investigated further by the HARPS spectrograph on ESO’s 3.6-metre telescope at La Silla, GJ 1214 b is the second super-Earth exoplanet for which astronomers have determined the mass and radius, giving vital clues about its structure. It is also the first super-Earth around which an atmosphere has been found. A search for additional planets using transit timing variations was negative.[3]

No transit-time variations have yet been found for this transit. As of 2012, "the given data does not allow us to conclude that there is a [second] planet in the mass range 0.1–5 Earth-masses and the period range 0.76–1.23 or 1.91–3.18 days."[11]

See also[edit]


  1. ^ Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034.  Vizier query form
  2. ^ a b c d e Skrutskie, M. F. et al. (2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708.  Vizier catalog entry
  3. ^ a b c d e f g h i Berta, Zachory K. et al. (2011). "The GJ1214 Super-Earth System: Stellar Variability, New Transits, and a Search for Additional Planets". The Astrophysical Journal 736 (1). 12. arXiv:1012.0518. Bibcode:2011ApJ...736...12B. doi:10.1088/0004-637X/736/1/12. 
  4. ^ a b c Rojas-Ayala, Bárbara et al. (2010). "Metal-rich M-Dwarf Planet Hosts: Metallicities with K-band Spectra". The Astrophysical Journal Letters 720 (1): L113–L118. arXiv:1007.4593. Bibcode:2010ApJ...720L.113R. doi:10.1088/2041-8205/720/1/L113. 
  5. ^ a b c "LHS 3275 -- High proper-motion Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-12-16. 
  6. ^ van Altena, William F. et al. The General Catalogue of Trigonometric Stellar Parallaxes. Yale University Observatory. ASIN B000UG5T6Y. Vizier catalog entry
  7. ^ a b c d e f g h Charbonneau, David et al. (2009). "A super-Earth transiting a nearby low-mass star". Nature 462 (7275): 891–894. arXiv:0912.3229. Bibcode:2009Natur.462..891C. doi:10.1038/nature08679. 
  8. ^ a b Lépine, Sébastien; Shara, Michael M. (2005). "A Catalog of Northern Stars with Annual Proper Motions Larger than 015 (LSPM-NORTH Catalog)". The Astronomical Journal 129 (3): 1483–1522. arXiv:astro-ph/0412070. Bibcode:2005AJ....129.1483L. doi:10.1086/427854.  Vizier catalog entry
  9. ^ a b Anglada-Escudé, Guillem; Rojas-Ayala, Bárbara; Boss, Alan P.; Weinberger, Alycia J.; Lloyd, James P. (2012). "GJ 1214b revised. Improved trigonometric parallax, stellar parameters, orbital solution, and bulk properties for the super-Earth GJ 1214b". arXiv:1210.8087v3 [astro-ph.EP]. Bibcode 2012arXiv1210.8087A.
  10. ^ a b c d David A. Aguilar (2009-12-16). "Astronomers Find Super-Earth Using Amateur, Off-the-Shelf Technology". Harvard-Smithsonian Center for Astrophysics. Retrieved December 16, 2009. 
  11. ^ a b Kennet B. W. Harpsøe, et al. (2012). "The Transiting System GJ1214". Astronomy & Astrophysics. arXiv:1207.3064. Bibcode:2013A&A...549A..10H. doi:10.1051/0004-6361/201219996. 

External links[edit]

Coordinates: Sky map 17h 15m 18.94s, +4° 57′ 49.7″