Key parameters at a glance

A radius of 1.66 Earth radii
A mass of 3.40 Earth masses
Surface gravity around 1.23 g
An orbital period of 9.125 days
Semi-major axis 0.0610 AU
Equilibrium temperature 401 K (128 °C)
Distance from Earth 30.80 light-years
Earth Similarity Index 0.692
Travel time at Voyager 1 speed 543,070 years
Almost certainly tidally locked to its host star given the close orbit

2 siblings around GJ 357

GJ 357 c shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
GJ 357 b	Rocky Terrestrial	1.20	1.84	3.931	518	2019
GJ 357 c this	Super-Earth	1.66	3.40	9.125	401	2019
GJ 357 d	Sub-Neptune	2.34	6.10	55.661	220	2019

GJ 357 c Planet Profile

Physical Specs

Radius

1.66 R⊕

Radius (Jupiter)

0.148 R♃

Mass

3.40 M⊕

Mass (Jupiter)

0.011 M♃

Density

4.08 g/cm³

Surface Gravity

1.23 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.692

HZ Position Inner

Controversial No

Discovery

Year 2019

Method Radial Velocity

Facility Multiple Observatories

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#469of 1176

top 39.8%

This planet

1.66R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-379 b 1.66 R⊕ Kepler-394 c 1.66 R⊕ Kepler-1497 b 1.66 R⊕

Metric	Earth	GJ 357 c	Jupiter
Radius (R⊕)	1.00	1.66	11.21
Mass (M⊕)	1.00	3.40	317.83
Density (g/cm³)	5.51	4.08	1.33
Surface Gravity (g)	1.00	1.23	2.53
Insolation (S⊕)	1.00	4.45	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	3.400 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HIP

HIP 47103

TIC

TIC 413248763

Gaia DR2

Gaia DR2 5664814198431308288

Gaia DR3

Gaia DR3 5664814198431308288

System

GJ 357

Percentile among Super-Earth cohort

Radius 1.660 R⊕ · percentile 59 / cohort 1176

Mass 3.400 M⊕ · percentile 55 / cohort 1176

Orbital period 9.12 d · percentile 62 / cohort 1164

Distance 9.44 pc · percentile 2 / cohort 1171

ESI 0.692 · percentile 85 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

9.125 days

Semi-major axis

0.0610 AU

Eccentricity

—

Inclination

— °

Year Length

A year here lasts approximately 9.12 Earth days (2.5% of a terrestrial year) at a mean orbital distance of 0.0610 AU.

Eq. Temperature

401K

(128 °C)

Insolation (S⊕)

4.45

Earth = 1.00

Earth Similarity (ESI)

0.692

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Luque et al. 2019

Instrument

Multiple Instruments

Publication

2019-08

Observation locale

Multiple Locales

Discovery cohort

Planets confirmed in 2019 at Multiple Observatories (8 shown).

Gl 49 b · Sub-Neptune GJ 357 d · Sub-Neptune HR 5183 b · Gas Giant NSVS 14256825 b · Gas Giant 7 CMa c · Gas Giant HD 213885 c · Neptune-like USco1556 b · Gas Giant USco1621 b · Gas Giant

Host System: GJ 357

Spectral Class

M-type red dwarf

Effective Temperature

3,505 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.337 R☉

Stellar Mass

0.342 M☉

Metallicity [Fe/H]

-0.12

Extended Stellar Properties

Surface gravity (log g)

4.940 dex

Stellar density

13.600 g/cm³

Systemic radial velocity

-34.60 km/s

Rotational v·sin i

2.00 km/s

Rotation period

77.80 days

Activity index (log R'HK)

-5.370

Metallicity ratio

[Fe/H]

Distance

9.44 parsec

Light-years 30.80 ly

V-band magnitude

10.91 mag

Voyager-speed travel 543,070 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

105.883 mas

Total Proper Motion

999.976 mas/yr

PM Right Ascension

138.69 mas/yr

PM Declination

-990.31 mas/yr

Galactic Cartesian (pc)

x = -0.752 · y = 0.546 · z = -0.369

Equatorial (J2000)

RA 144.00746° · Dec -21.66506°

Galactic ℓ, b

253.888° · 22.080°

Ecliptic λ, β

154.771° · -33.777°

HTM-20 index

-465961619