GJ 1252

GJ 1252
Observation data; Epoch J2000 Equinox ICRS
Constellation	Telescopium
Right ascension	20h 27m 42.08140s
Declination	−56° 27′ 25.1519″
Apparent magnitude (V)	12.193
Characteristics
Evolutionary stage	Main sequence
Spectral type	M2.5V
Apparent magnitude (B)	13.655±0.029
Apparent magnitude (V)	12.193±0.056
Apparent magnitude (G)	11.235±0.003
Apparent magnitude (J)	8.697±0.019
Apparent magnitude (H)	8.161±0.034
Apparent magnitude (K)	7.915±0.023
Astrometry
Radial velocity (Rv)	7.38±0.29 km/s
Proper motion (μ)	RA: 424.417 mas/yr ; Dec.: −1,230.941 mas/yr
Parallax (π)	49.0555±0.0247 mas
Distance	66.49 ± 0.03 ly ; (20.39 ± 0.01 pc)
Details
Mass	0.381±0.008 M☉
Radius	0.391±0.012 R☉
Luminosity (bolometric)	0.0196+0.0026; −0.0023 L☉
Surface gravity (log g)	4.83±0.03 cgs
Temperature	3,458+140; −133 K
Metallicity [Fe/H]	−0.18±0.13 dex
Age	3.9±0.4 Gyr
Other designations
	GJ 1252, L 210-70, LFT 1546, LHS 492, LTT 8083, NLTT 49258, PM J20277-5627, TOI-1078, TIC 370133522, GCRV 26183, 2MASS J20274210-5627262
Database references
SIMBAD	data
Exoplanet Archive	data
ARICNS	data

GJ 1252 is a red dwarf star located 66.5 light-years (20.4 parsecs) away from the Solar System in the constellation of Telescopium. The star has about 38% the mass and 39% the radius of the Sun, and a temperature of about 3,458 K (3,185 °C; 5,765 °F). GJ 1252 is orbited by one known exoplanet.

Planetary system

GJ 1252 was found to have a planet, GJ 1252 b, in 2019 using transit observations from TESS. It is a terrestrial planet larger than Earth, with about 1.3 times the mass and 1.18 times the radius of Earth. Orbiting its star with a very short period of just 12.4 hours, it is presumably tidally locked. Secondary eclipse observations have shown that GJ 1252 b lacks a significant atmosphere, similar to LHS 3844 b and TRAPPIST-1b, and have measured its dayside temperature at about 1,410 K (1,140 °C; 2,080 °F).

A candidate second planet was identified in 2022 with Doppler spectroscopy (radial velocity method), named GJ 1252 c. It orbits with a period of 18.41 days and has a mass of at least 6.08 M_🜨. The existence of this planet in uncertain, as the radial velocity variations may be intrinsic to the star rather than due to the gravitational pull of an orbiting body.

The GJ 1252 planetary system
Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination (°)	Radius
b	1.54±0.18 `M`_🜨	0.00915±0.00015	0.51824160	0	84.8±3.2	1.19±0.05 `R`_🜨
c (unconfirmed)	≥6.08±0.86 `M`_🜨	—	18.41±0.01	0.20+0.11 −0.10	—	—

References

↑ 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.
1 2 3 4 5 6 7 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.
1 2 3 4 5 6 7 8 9 10 Shporer, Avi; Collins, Karen A.; et al. (February 2020). "GJ 1252 b: A 1.2 R⊕ Planet Transiting an M3 Dwarf at 20.4 pc". The Astrophysical Journal Letters. 890 (1): L7. arXiv:1912.05556. Bibcode:2020ApJ...890L...7S. doi:10.3847/2041-8213/ab7020.
↑ Reid, I. Neill; et al. (October 1995). "The Palomar/MSU Nearby-Star Spectroscopic Survey. I. The Northern M Dwarfs -Bandstrengths and Kinematics". Astronomical Journal. 110: 1838. Bibcode:1995AJ....110.1838R. doi:10.1086/117655.
1 2 3 4 5 6 7 8 9 10 Weisserman, Drew; Gromek, Nicole; Cloutier, Ryan; Bali, Komal; Cadieux, Charles; Plotnykov, Mykhaylo; L'Heureux, Alexandrine; Srivastava, Avidaan; Carmona, Andres (2026-04-08). "Super-Earth masses and stellar abundances from NIRPS reveal tentative evidence for water-rich formation around M dwarfs". Astronomy & Astrophysics. arXiv:2604.07447.
1 2 3 4 5 Crossfield, Ian J. M.; Malik, Matej; et al. (September 2022). "GJ 1252b: A Hot Terrestrial Super-Earth with No Atmosphere". The Astrophysical Journal Letters. 937 (1): L17. arXiv:2208.09479. Bibcode:2022ApJ...937L..17C. doi:10.3847/2041-8213/ac886b.
↑ "GJ 1252". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 May 2023.
1 2 Gohd, Chelsea (11 October 2022). "Discovery Alert: Ultra-hot 'Super-Earth' Could Have No Atmosphere". NASA. Retrieved 8 May 2023.
1 2 Luque, Rafael; Pallé, Enric (2022-09-09). "Density, not radius, separates rocky and water-rich small planets orbiting M dwarf stars". Science. 377 (6611): 1211–1214. arXiv:2209.03871. doi:10.1126/science.abl7164.

[Roman1987-1] 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.

[GaiaDR3-2] 1 2 3 4 5 6 7 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.

[Shporer2020-3] 1 2 3 4 5 6 7 8 9 10 Shporer, Avi; Collins, Karen A.; et al. (February 2020). "GJ 1252 b: A 1.2 R⊕ Planet Transiting an M3 Dwarf at 20.4 pc". The Astrophysical Journal Letters. 890 (1): L7. arXiv:1912.05556. Bibcode:2020ApJ...890L...7S. doi:10.3847/2041-8213/ab7020.

[reid1995-4] Reid, I. Neill; et al. (October 1995). "The Palomar/MSU Nearby-Star Spectroscopic Survey. I. The Northern M Dwarfs -Bandstrengths and Kinematics". Astronomical Journal. 110: 1838. Bibcode:1995AJ....110.1838R. doi:10.1086/117655.

[Weisserman2026-5] 1 2 3 4 5 6 7 8 9 10 Weisserman, Drew; Gromek, Nicole; Cloutier, Ryan; Bali, Komal; Cadieux, Charles; Plotnykov, Mykhaylo; L'Heureux, Alexandrine; Srivastava, Avidaan; Carmona, Andres (2026-04-08). "Super-Earth masses and stellar abundances from NIRPS reveal tentative evidence for water-rich formation around M dwarfs". Astronomy & Astrophysics. arXiv:2604.07447.

[Crossfield2022-6] 1 2 3 4 5 Crossfield, Ian J. M.; Malik, Matej; et al. (September 2022). "GJ 1252b: A Hot Terrestrial Super-Earth with No Atmosphere". The Astrophysical Journal Letters. 937 (1): L17. arXiv:2208.09479. Bibcode:2022ApJ...937L..17C. doi:10.3847/2041-8213/ac886b.

[SIMBAD-7] "GJ 1252". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 May 2023.

[NASA-20221011-8] 1 2 Gohd, Chelsea (11 October 2022). "Discovery Alert: Ultra-hot 'Super-Earth' Could Have No Atmosphere". NASA. Retrieved 8 May 2023.

[Luque2022-9] 1 2 Luque, Rafael; Pallé, Enric (2022-09-09). "Density, not radius, separates rocky and water-rich small planets orbiting M dwarf stars". Science. 377 (6611): 1211–1214. arXiv:2209.03871. doi:10.1126/science.abl7164.