Gliese 357

GJ 357 (Gliese 357) is an M-type main sequence star with an unusually low star spot activity.^[9] It is located 31 light-years from the Solar System,^[10] in the Hydra constellation.^[10]

Gliese 357

Artist concept of the Gliese 357 (GJ357) system. Credit: Jack Madden
Observation data Epoch J2000      Equinox J2000
Constellation	Hydra[1]
Right ascension	09h 36m 01.63722s[2]
Declination	−21° 39′ 38.8776″[2]
Apparent magnitude (V)	10.906[3]
Characteristics
Evolutionary stage	main sequence[4]
Spectral type	M2.5V[5]
Astrometry
Radial velocity (Rv)	−35.03±0.17[2] km/s
Proper motion (μ)	RA: 138.722±0.023 mas/yr[2] Dec.: −990.342±0.020 mas/yr[2]
Parallax (π)	105.9789±0.0227 mas[2]
Distance	30.776 ± 0.007 ly (9.436 ± 0.002 pc)
Absolute magnitude (MV)	+11.13[6]
Details
Mass	0.362[4] M☉
Radius	0.333[6] R☉
Luminosity	0.014[7] L☉
Surface gravity (log g)	4.96[4] cgs
Temperature	3,488[4] K
Metallicity [Fe/H]	−0.14[4] dex
Rotation	74.3±1.7 d[8]
Rotational velocity (v sin i)	2.5[4] km/s
Other designations
HIP 47103, TOI-562, 2MASS 09360161-2139371
Database references
SIMBAD	data
Exoplanet Archive	data

Planetary system

The star has three confirmed exoplanets in its orbit. ^[11] One of these, Gliese 357 d, is considered to be a "super-Earth" within the circumstellar habitable zone.^{[12][10][13][14]}

Transiting planets b and c are close to 3:7 mean-motion resonance. Presuming resonance chain extends to the outermost, cold, possibly terrestrial Gliese 357 d and the resonances are simple. Transmission spectroscopy of the planet b with JWST in 2025 found no clear evidence for atmospheric molecules, although a secondary atmosphere is considered likely to exist.^[15]

The Gliese 357 planetary system^[16]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	1.84±0.31 M🜨	0.035±0.002	3.93072+0.00008 −0.00006	0.047+0.059 −0.047	89.12+0.37 −0.31°	1.217+0.084 −0.083 R🜨
c	≥3.40±0.46 M🜨	0.061±0.004	9.1247+0.0011 −0.0010	0.072±0.053	—	—
d	≥6.1±1.0 M🜨	0.204±0.015	55.661±0.055	0.033+0.057 −0.033	—	—