Gliese 12#Planetary system
{{Short description|Red dwarf star}}
{{Starbox begin}}
{{Starbox image
| image = 250px
| caption = Artist's impression of Gliese 12 and its planet (foreground)
}}
{{Starbox observe
| epoch = J2000
| constell = Pisces
| dec = {{DEC|+13|33|22.3163}}
}}
{{Starbox character
| type = main sequence
| appmag_1_passband = V
| appmag_1 = {{val|12.600|0.04}}
| appmag_2_passband = R
| appmag_2 = {{val|12.296|0.08}}
| appmag_3_passband = G
| appmag_3 = {{val|11.399|0.003}}
| appmag_4_passband = J
| appmag_4 = {{val|8.619|0.020}}
| appmag_5_passband = H
| appmag_5 = {{val|8.068|0.026}}
| appmag_6_passband = K
| appmag_6 = {{val|7.807|0.020}}
}}
{{Starbox astrometry
| radial_v = {{val|51.04|0.26}}
| prop_mo_ra = 618.065
| prop_mo_dec = 329.446
| parallax = 82.1938
| p_error = 0.0326
| absmag_v =
| absmag_bol =
}}
{{Starbox detail
| mass = {{val|0.2414|0.0060}}
| radius = {{val|0.2617|0.0058|0.0070}}
| luminosity_bolometric = 0.00728{{±|0.00015}}
| gravity = {{val|5.21|0.07}}
| temperature = {{val|3296|48|36|fmt=commas}}
| metal_fe = {{val|−0.32|0.06}}
| rotation = 85 days
| rotational_velocity = <2
| age_gyr = {{val|7.0|2.8|2.2}}
}}
{{Starbox catalog
| names = {{odlist | 2MASS = J00154919+1333218 | G = 32-5 | GJ = 12 | L = 1154-29 | LHS = 1050 | LP = 464-42 | LTT = 10083 | NLTT = 786 | PLX = 42 | TIC = 52005579 | TOI = 6251}}
}}
{{Starbox reference
| Simbad = GJ+12
| NSTED = GJ-12
}}
{{Starbox end}}
Gliese 12 (GJ 12) is a red dwarf star located {{convert|39.7|ly|pc|lk=on|abbr=off}} away in the constellation Pisces. It has about 24% the mass and 26% the radius of the Sun, and a temperature of about {{convert|3296|K|C F|lk=on}}. It is an inactive star and hosts one known exoplanet.
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. Gliese 12 b is similar in size to Earth and Venus, and completes an orbit around its star every 12.8 days.
Initially its mass was poorly constrained but was determined to be less than 4 times that of Earth. Measurements gathered in 2025 studies provided mass measurements of 0.71 and 0.95 Earth masses ({{earth mass}}). The latter also measured a planetary radius of {{earth radius|0.934|link=y}}, and found a density of {{val|7.0|2.3|2.1|ul=g/cm3}}, higher than the densities of the Solar System's terrestrial planets. This suggests a likely rocky composition, similar to Venus. While this, the former study used the discovery paper's radius ({{earth radius|0.958}}) 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.
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. 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. Its equilibrium temperature, assuming an albedo of zero, is {{convert|315|K|C F|lk=on}}; if it has an atmosphere, the surface temperature would be greater than this. Assuming an albedo similar to Venus, the equilibrium temperature is {{convert|218|K|C F}}.
{{Orbitbox planet begin
| table_ref = {{Efn|Semi-major axis from Kuzuhara et al. (2024), radius, orbital period and inclination from Turner et al. (2025).}}
}}
{{Orbitbox planet
| exoplanet = b
| mass_earth = {{val|0.71|0.12}} or {{val|0.95|0.26|0.27}}
| radius_earth = {{val|0.904|0.037|0.034}}
| semimajor = {{val|0.0668|0.0024}}
| period = {{val|12.761421|(47)}}
| eccentricity = {{val|0.16|0.14|0.09}} or {{val|0.25|0.13}}
| inclination = {{val|89.236|0.069|0.061}}
}}
{{Orbitbox end}}
Notes
{{Notelist}}
References
{{reflist|refs=
{{cite simbad |title=GJ 12 |access-date=23 May 2024}}
{{Cite Gaia DR3|2768048564768256512}}
{{cite journal |last1=Newton |first1=Elisabeth R. |last2=Charbonneau |first2=David |display-authors=etal |date=January 2014 |title=Near-infrared Metallicities, Radial Velocities, and Spectral Types for 447 Nearby M Dwarfs |journal=The Astronomical Journal |volume=147 |issue=1 |pages=20 |doi=10.1088/0004-6256/147/1/20 |doi-access=free |arxiv=1310.1087 |bibcode=2014AJ....147...20N}}
{{cite journal |last1=Kuzuhara |first1=Masayuki |last2=Fukui |first2=Akihiko |display-authors=etal |date=23 May 2024 |title=Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Transmission Spectroscopy |journal=The Astrophysical Journal Letters |volume=967 |issue=2 |pages=L21 |doi=10.3847/2041-8213/ad3642 |doi-access=free |arxiv=2405.14708 |bibcode=2024ApJ...967L..21K}}
{{cite constellation|Gliese 12}}
{{cite journal |last1=Dholakia |first1=Shishir |last2=Palethorpe |first2=Larissa |display-authors=etal |date=23 May 2024 |title=Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TESS and CHEOPS |journal=Monthly Notices of the Royal Astronomical Society |volume=531 |issue=1 |pages=1276–1293 |doi=10.1093/mnras/stae1152 |doi-access=free |arxiv=2405.13118 |bibcode=2024MNRAS.531.1276D}}
{{cite web |url=https://science.nasa.gov/universe/exoplanets/nasas-tess-finds-intriguing-world-sized-between-earth-venus/ |title=NASA's TESS Finds Intriguing World Sized Between Earth, Venus |last=Reddy |first=Francis |date=23 May 2024 |publisher=NASA |access-date=23 May 2024 |archive-date=23 May 2024 |archive-url=https://web.archive.org/web/20240523142150/https://science.nasa.gov/universe/exoplanets/nasas-tess-finds-intriguing-world-sized-between-earth-venus/ |url-status=live }}
}}
{{2024 in space}}
{{Pisces (constellation)}}
Category:Pisces (constellation)
Category:M-type main-sequence stars