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Gliese 12

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Gliese 12

Artist's impression of Gliese 12 and its planet (foreground)
Observation data
Epoch J2000      Equinox J2000
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 mas/yr[2]
Dec.: 329.446 mas/yr[2]
Parallax (π)82.1938±0.0326 mas[2]
Distance39.68 ± 0.02 ly
(12.166 ± 0.005 pc)
Details[5]
Mass0.2414±0.0060 M☉
Radius0.2617+0.0058
−0.0070 R☉
Luminosity (bolometric)0.00728±0.00015 L☉
Surface gravity (log g)5.21±0.07 cgs
Temperature3,296+48
−36 K
Metallicity [Fe/H]−0.32±0.06 dex
Rotation85 days
Rotational velocity (v sin i)<2 km/s
Age7.0+2.8
−2.2[6] Gyr
Other designations
GJ 12, G 32-5, L 1154-29, LHS 1050, LP 464-42, LTT 10083, NLTT 786, PLX 42, TOI-6251, TIC 52005579, 2MASS J00154919+1333218[3]
Database references
SIMBADdata
Exoplanet Archivedata

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

[edit]

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 (ME).[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]

The Gliese 12 planetary system[a]
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

[edit]
  1. ^ Semi-major axis from Kuzuhara et al. (2024),[5] radius, orbital period and inclination from Turner et al. (2025).[7]

References

[edit]
  1. ^ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
  2. ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. ^ a b c d e f g "GJ 12". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 23 May 2024.
  4. ^ Newton, Elisabeth R.; Charbonneau, David; et al. (January 2014). "Near-infrared Metallicities, Radial Velocities, and Spectral Types for 447 Nearby M Dwarfs". The Astronomical Journal. 147 (1): 20. arXiv:1310.1087. Bibcode:2014AJ....147...20N. doi:10.1088/0004-6256/147/1/20.
  5. ^ a b c d e f Kuzuhara, Masayuki; Fukui, Akihiko; 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. arXiv:2405.14708. Bibcode:2024ApJ...967L..21K. doi:10.3847/2041-8213/ad3642.
  6. ^ a b c Dholakia, Shishir; Palethorpe, Larissa; 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. arXiv:2405.13118. Bibcode:2024MNRAS.531.1276D. doi:10.1093/mnras/stae1152.
  7. ^ a b c d e f g h 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. ^ a b c d 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].
  9. ^ Reddy, Francis (23 May 2024). "NASA's TESS Finds Intriguing World Sized Between Earth, Venus". NASA. Archived from the original on 23 May 2024. Retrieved 23 May 2024.
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