Key parameters at a glance

A radius of 1.17 Earth radii
A mass of 1.71 Earth masses
Surface gravity around 1.25 g
An orbital period of 7.027 days
Semi-major axis 0.0540 AU
Equilibrium temperature 485 K (212 °C)
Distance from Earth 22.93 light-years
Earth Similarity Index 0.639
Travel time at Voyager 1 speed 404,434 years
Almost certainly tidally locked to its host star given the close orbit

GJ 393 b Planet Profile

Physical Specs

Radius

1.17 R⊕

Radius (Jupiter)

0.104 R♃

Mass

1.71 M⊕

Mass (Jupiter)

0.005 M♃

Density

5.87 g/cm³

Surface Gravity

1.25 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.639

HZ Position Inner

Controversial No

Discovery

Year 2021

Method Radial Velocity

Facility Multiple Observatories

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#135of 570

top 23.5%

This planet

1.17R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-339 d 1.17 R⊕ Kepler-185 b 1.17 R⊕ TOI-1442 b 1.17 R⊕

Metric	Earth	GJ 393 b	Jupiter
Radius (R⊕)	1.00	1.17	11.21
Mass (M⊕)	1.00	1.71	317.83
Density (g/cm³)	5.51	5.87	1.33
Surface Gravity (g)	1.00	1.25	2.53
Insolation (S⊕)	1.00	9.21	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	1.710 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HIP

HIP 51317

TIC

TIC 277888583

Gaia DR2

Gaia DR2 3855208897392952192

Gaia DR3

Gaia DR3 3855208897392952192

System

GJ 393

Percentile among Rocky Terrestrial cohort

Radius 1.170 R⊕ · percentile 75 / cohort 570

Mass 1.710 M⊕ · percentile 69 / cohort 570

Orbital period 7.03 d · percentile 68 / cohort 567

Distance 7.03 pc · percentile 4 / cohort 566

ESI 0.639 · percentile 80 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

7.027 days

Semi-major axis

0.0540 AU

Eccentricity

—

Inclination

— °

Year Length

A year here lasts approximately 7.03 Earth days (1.9% of a terrestrial year) at a mean orbital distance of 0.0540 AU.

Eq. Temperature

485K

(212 °C)

Insolation (S⊕)

9.21

Earth = 1.00

Earth Similarity (ESI)

0.639

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

Amado et al. 2021

Instrument

Multiple Instruments

Publication

2021-06

Observation locale

Ground

Discovery cohort

Planets confirmed in 2021 at Multiple Observatories (12 shown).

L 98-59 e · Super-Earth HD 168009 b · Sub-Neptune HD 164922 e · Sub-Neptune HD 95735 c · Sub-Neptune HD 141004 b · Sub-Neptune HD 107148 c · Neptune-like TOI-178 f · Sub-Neptune TYC 0434-04538-1 b · Gas Giant HIP 56640 b · Gas Giant HD 137496 c · Gas Giant HD 156668 c · Neptune-like HD 145675 c · Gas Giant

Host System: GJ 393

Spectral Class

M-type red dwarf

Effective Temperature

3,579 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.426 R☉

Stellar Mass

0.426 M☉

Metallicity [Fe/H]

-0.09

Extended Stellar Properties

Surface gravity (log g)

4.880 dex

Stellar density

7.436 g/cm³

Systemic radial velocity

8.30 km/s

Rotational v·sin i

2.00 km/s

Rotation period

34.15 days

Metallicity ratio

[Fe/H]

Distance

7.03 parsec

Light-years 22.93 ly

V-band magnitude

9.65 mag

Voyager-speed travel 404,434 yr

Multi-band Host Photometry — 14 bands

Astrometric Data

Parallax

142.188 mas

Total Proper Motion

948.444 mas/yr

PM Right Ascension

-603.00 mas/yr

PM Declination

-732.08 mas/yr

Galactic Cartesian (pc)

x = -0.922 · y = 0.387 · z = 0.015

Equatorial (J2000)

RA 157.22887° · Dec 0.83785°

Galactic ℓ, b

244.476° · 46.883°

Ecliptic λ, β

158.619° · -8.078°

HTM-20 index

115086692