GJ 1214
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 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] |
| Characteristics | |
| 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] |
| Astrometry | |
| 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 |
| Details | |
| Mass | 0.157 ± 0.019[7] M☉ |
| Radius | 0.2064+0.0086 −0.0096[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 | 6 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 | |
| SIMBAD | data |
| Exoplanet Archive | data |
| ARICNS | data |
| Extrasolar Planets Encyclopaedia | data |
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
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]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
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⊕ |
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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
- COROT-7
- Gliese 581
- Gliese 876
- List of extrasolar planets
References
- ↑ 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
- ↑ 2.0 2.1 2.2 2.3 2.4 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
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 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.
- ↑ 4.0 4.1 4.2 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.
- ↑ 5.0 5.1 5.2 "LHS 3275 -- High proper-motion Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-12-16.
- ↑ van Altena, William F. et al. The General Catalogue of Trigonometric Stellar Parallaxes. Yale University Observatory. ASIN B000UG5T6Y.Vizier catalog entry
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 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.
- ↑ 8.0 8.1 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
- ↑ 9.0 9.1 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.
- ↑ 10.0 10.1 10.2 10.3 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.
- ↑ 11.0 11.1 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
Coordinates: 
17h 15m 18.94s, +4° 57′ 49.7″
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