Key parameters at a glance

A radius of 2.30 Earth radii
A mass of 5.89 Earth masses
Surface gravity around 1.11 g
An orbital period of 32.761 days
Semi-major axis 0.1617 AU
Equilibrium temperature 291 K (17 °C)
Distance from Earth 33.95 light-years
Earth Similarity Index 0.788
Travel time at Voyager 1 speed 598,712 years
Almost certainly tidally locked to its host star given the close orbit

1 sibling around GJ 536

GJ 536 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
GJ 536 b	Sub-Neptune	2.41	6.37	8.709	451	2016
GJ 536 c this	Sub-Neptune	2.30	5.89	32.761	291	2025

GJ 536 c Planet Profile

Physical Specs

Radius

2.30 R⊕

Radius (Jupiter)

0.205 R♃

Mass

5.89 M⊕

Mass (Jupiter)

0.019 M♃

Density

2.66 g/cm³

Surface Gravity

1.11 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.788

HZ Position Inner

Controversial No

Discovery

Year 2025

Method Radial Velocity

Facility Multiple Facilities

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#1499of 1978

top 75.7%

This planet

2.30R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-328 b 2.30 R⊕ K2-22 b 2.30 R⊕ Kepler-156 b 2.30 R⊕

Metric	Earth	GJ 536 c	Jupiter
Radius (R⊕)	1.00	2.30	11.21
Mass (M⊕)	1.00	5.89	317.83
Density (g/cm³)	5.51	2.66	1.33
Surface Gravity (g)	1.00	1.11	2.53
Insolation (S⊕)	1.00	1.69	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	5.890 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 122303

HIP

HIP 68469

TIC

TIC 119147875

Gaia DR2

Gaia DR2 3657653114880309248

Gaia DR3

Gaia DR3 3657653114880309248

System

GJ 536

Percentile among Sub-Neptune cohort

Radius 2.300 R⊕ · percentile 24 / cohort 1978

Mass 5.890 M⊕ · percentile 23 / cohort 1978

Orbital period 32.76 d · percentile 75 / cohort 1946

Distance 10.41 pc · percentile 2 / cohort 1975

ESI 0.788 · percentile 99 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

32.761 days

Semi-major axis

0.1617 AU

Eccentricity

0.000

Inclination

— °

Year Length

A year here lasts approximately 32.76 Earth days (9.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1617 AU.

Eq. Temperature

291K

(17 °C)

Insolation (S⊕)

1.69

Earth = 1.00

Earth Similarity (ESI)

0.788

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — liquid water is physically possible with adequate atmospheric pressure. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Suarez Mascareno et al. 2025

Instrument

Multiple Instruments

Publication

2025-10

Observation locale

Ground

Host System: GJ 536

Spectral Class

M-type red dwarf

Effective Temperature

3,641 K — cooler than the Sun (5,778 K)

Estimated Age

4.20 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.529 R☉

Stellar Mass

0.528 M☉

Metallicity [Fe/H]

-0.08

Extended Stellar Properties

Surface gravity (log g)

4.713 dex

Stellar density

5.445 g/cm³

Systemic radial velocity

-25.62 km/s

Rotational v·sin i

1.20 km/s

Rotation period

43.63 days

Activity index (log R'HK)

-5.120

Metallicity ratio

[Fe/H]

Distance

10.41 parsec

Light-years 33.95 ly

V-band magnitude

9.71 mag

Voyager-speed travel 598,712 yr

Multi-band Host Photometry — 13 bands

Astrometric Data

Parallax

96.040 mas

Total Proper Motion

1,019.344 mas/yr

PM Right Ascension

-825.42 mas/yr

PM Declination

598.11 mas/yr

Galactic Cartesian (pc)

x = -0.863 · y = -0.503 · z = -0.046

Equatorial (J2000)

RA 210.25973° · Dec -2.65229°

Galactic ℓ, b

335.052° · 55.817°

Ecliptic λ, β

209.097° · 9.078°

HTM-20 index

-129712442

Observation Record

Photometric series

Stellar spectra

Archive notes