Key parameters at a glance

A radius of 2.34 Earth radii
A mass of 6.10 Earth masses
Surface gravity around 1.11 g
An orbital period of 55.661 days
Semi-major axis 0.2040 AU
Equilibrium temperature 220 K (-54 °C)
Distance from Earth 30.80 light-years
Earth Similarity Index 0.644
Travel time at Voyager 1 speed 543,070 years

Context from the literature

Gliese 357 d is an exoplanet, considered to be a "Super-Earth" within the circumstellar habitable zone of its parent star. The planet orbits Gliese 357, 31 light-years from the Solar System, The system is part of the Hydra constellation.

Excerpted from Wikipedia · full article

2 siblings around GJ 357

GJ 357 d 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	Super-Earth	1.66	3.40	9.125	401	2019
GJ 357 d this	Sub-Neptune	2.34	6.10	55.661	220	2019

GJ 357 d Planet Profile

Physical Specs

Radius

2.34 R⊕

Radius (Jupiter)

0.209 R♃

Mass

6.10 M⊕

Mass (Jupiter)

0.019 M♃

Density

2.62 g/cm³

Surface Gravity

1.11 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.644

HZ Position Habitable

Controversial No

Discovery

Year 2019

Method Radial Velocity

Facility Multiple Observatories

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#1429of 1978

top 72.2%

This planet

2.34R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-246 b 2.34 R⊕ Kepler-275 b 2.34 R⊕ Kepler-338 c 2.34 R⊕

Metric	Earth	GJ 357 d	Jupiter
Radius (R⊕)	1.00	2.34	11.21
Mass (M⊕)	1.00	6.10	317.83
Density (g/cm³)	5.51	2.62	1.33
Surface Gravity (g)	1.00	1.11	2.53
Insolation (S⊕)	1.00	0.38	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	6.100 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 Sub-Neptune cohort

Radius 2.340 R⊕ · percentile 27 / cohort 1978

Mass 6.100 M⊕ · percentile 27 / cohort 1978

Orbital period 55.66 d · percentile 87 / cohort 1946

Distance 9.44 pc · percentile 1 / cohort 1975

ESI 0.644 · percentile 87 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

55.661 days

Semi-major axis

0.2040 AU

Eccentricity

—

Inclination

— °

Year Length

A year here lasts approximately 55.66 Earth days (15.2% of a terrestrial year) at a mean orbital distance of 0.2040 AU.

Eq. Temperature

220K

(-54 °C)

Insolation (S⊕)

0.38

Earth = 1.00

Earth Similarity (ESI)

0.644

0 = alien, 1 = Earth-identical

Within the conservative habitable zone — surface water would be frozen.

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 c · Super-Earth 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

Wikipedia → Image: Wikimedia Commons · NASA's Goddard Space Flight Center/Chris Smith · Public domain