Astronomy:Gliese 12
250px Artist's impression of Gliese 12 and its planet (foreground) | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Pisces[1] |
| Right ascension | 00h 15m 49.24231s[2] |
| Declination | +13° 33′ 22.3163″[2] |
| Apparent magnitude (V) | 12.6[3] |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | M4V[4] |
| Apparent magnitude (V) | 12.600±0.04[3] |
| Apparent magnitude (R) | 12.296±0.08[3] |
| Apparent magnitude (G) | 11.399±0.003[2] |
| Apparent magnitude (J) | 8.619±0.020[3] |
| Apparent magnitude (H) | 8.068±0.026[3] |
| Apparent magnitude (K) | 7.807±0.020[3] |
| Astrometry | |
| Radial velocity (Rv) | 51.04±0.26[2] km/s |
| Proper motion (μ) | RA: 618.065[2] mas/yr Dec.: 329.446[2] mas/yr |
| Parallax (π) | 82.1938 ± 0.0326[2] mas |
| Distance | 39.68 ± 0.02 ly (12.166 ± 0.005 pc) |
| Details[5] | |
| Mass | 0.2414±0.0060 M☉ |
| Radius | 0.2617+0.0058 −0.0070 R☉ |
| Luminosity (bolometric) | 0.00728±0.00015 L☉ |
| Surface gravity (log g) | 5.21±0.07 cgs |
| Temperature | 3,296+48 −36 K |
| Metallicity [Fe/H] | −0.32±0.06 dex |
| Rotation | 85 days |
| Rotational velocity (v sin i) | <2 km/s |
| Age | 7.0+2.8 −2.2[6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Gliese 12 (GJ 12) is a red dwarf star located 39.7 light-years (12.2 parsecs) away in the constellation Pisces. It has about 24% the mass and 26% the radius of the Sun, and a temperature of about 3,296 K (3,023 °C; 5,473 °F). It is an inactive star and hosts one known exoplanet.[5]
Planetary system
The transiting exoplanet Gliese 12 b was discovered by TESS, and two independent studies confirming it as a planet were published in May 2024.[5][6] Gliese 12 b is similar in size to Earth and Venus, and completes an orbit around its star every 12.8 days.[7]
Initially its mass was poorly constrained but was determined to be less than 4 times that of Earth.[5] Measurements gathered in 2025 studies provided mass measurements of 0.71[8] and 0.95 Earth masses (M⊕).[7] The latter also measured a planetary radius of 0.934 R⊕, and found a density of 7.0+2.3
−2.1 g/cm3, higher than the densities of the Solar System's terrestrial planets. This suggests a likely rocky composition, similar to Venus.[7] While this, the former study used the discovery paper's radius (0.958 R⊕) and found a lower density that give less constraints on its composition. Scenarios such as an Earth-like composition, volatile-dominated composition, iron-poor, or even a combination are all plausible.[8]
Along with the planets of TRAPPIST-1 and LHS 1140 b, Gliese 12 b is one of the nearest known relatively temperate transiting exoplanets, and so is a promising target for the James Webb Space Telescope to determine whether it has retained an atmosphere.[9][7] Gliese 12 b orbits slightly closer than the inner edge of its star's habitable zone, with an insolation between those of Earth and Venus.[6] Its equilibrium temperature, assuming an albedo of zero, is 315 K (42 °C; 107 °F); if it has an atmosphere, the surface temperature would be greater than this.[5] Assuming an albedo similar to Venus, the equilibrium temperature is 218 K (−55 °C; −67 °F).[7]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.71±0.12[8] or 0.95+0.26 −0.27[7] M⊕ |
0.0668±0.0024 | 12.761421(47) | 0.16+0.14 −0.09[8] or 0.25±0.13[7] |
89.236+0.069 −0.061° |
0.904+0.037 −0.034 R⊕ |
Notes
References
- ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific 99 (617): 695. doi:10.1086/132034. Bibcode: 1987PASP...99..695R Constellation record for this object at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 "GJ 12". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=GJ+12.
- ↑ Newton, Elisabeth R. et al. (January 2014). "Near-infrared Metallicities, Radial Velocities, and Spectral Types for 447 Nearby M Dwarfs". The Astronomical Journal 147 (1): 20. doi:10.1088/0004-6256/147/1/20. Bibcode: 2014AJ....147...20N.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Kuzuhara, Masayuki et al. (23 May 2024). "Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Transmission Spectroscopy". The Astrophysical Journal Letters 967 (2): L21. doi:10.3847/2041-8213/ad3642. Bibcode: 2024ApJ...967L..21K.
- ↑ 6.0 6.1 6.2 Dholakia, Shishir et al. (23 May 2024). "Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TESS and CHEOPS". Monthly Notices of the Royal Astronomical Society 531 (1): 1276–1293. doi:10.1093/mnras/stae1152. Bibcode: 2024MNRAS.531.1276D.
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 Turner, Daisy A.; et al. (2025). "The mass of the exo-Venus Gliese 12 b, as revealed by HARPS-N, ESPRESSO, and CARMENES". arXiv:2506.20564 [astro-ph.EP].
- ↑ 8.0 8.1 8.2 8.3 Brady, Madison; Bean, Jacob; Basant, Ritvik; Brown, Nina; Das, Tanya; Nixon, Matthew; Luque, Rafael; Piaulet-Ghorayeb, Caroline; Radica, Michael (2025-06-25). "An Earth-like Density for the Temperate Earth-sized Planet GJ 12b". arXiv:2506.20561 [astro-ph.EP].
- ↑ Reddy, Francis (23 May 2024). "NASA's TESS Finds Intriguing World Sized Between Earth, Venus". NASA. https://science.nasa.gov/universe/exoplanets/nasas-tess-finds-intriguing-world-sized-between-earth-venus/.
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