Key parameters at a glance

A radius of 4.22 Earth radii
A mass of 16.57 Earth masses
Surface gravity around 0.93 g
An orbital period of 13.352 days
Semi-major axis 0.0820 AU
Distance from Earth 69.59 light-years
Earth Similarity Index 0.527
Travel time at Voyager 1 speed 1,227,207 years
Almost certainly tidally locked to its host star given the close orbit

GJ 4276 b Planet Profile

Physical Specs

Radius

4.22 R⊕

Radius (Jupiter)

0.377 R♃

Mass

16.57 M⊕

Mass (Jupiter)

0.052 M♃

Density

1.21 g/cm³

Surface Gravity

0.93 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.527

HZ Position Unknown

Controversial No

Discovery

Year 2019

Method Radial Velocity

Facility Calar Alto Observatory

Telescope 3.5 m telescope

Size rank in cohort

Rank by radius

#513of 574

top 89.2%

This planet

4.22R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

Kepler-584 b 4.21 R⊕ Kepler-953 b 4.21 R⊕ Kepler-149 b 4.21 R⊕

Metric	Earth	GJ 4276 b	Jupiter
Radius (R⊕)	1.00	4.22	11.21
Mass (M⊕)	1.00	16.57	317.83
Density (g/cm³)	5.51	1.21	1.33
Surface Gravity (g)	1.00	0.93	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	16.570 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

TIC

TIC 428238233

Gaia DR2

Gaia DR2 2200501793758177152

Gaia DR3

Gaia DR3 2200501793758177152

System

GJ 4276

Percentile among Neptune-like cohort

Radius 4.220 R⊕ · percentile 11 / cohort 574

Mass 16.570 M⊕ · percentile 16 / cohort 574

Orbital period 13.35 d · percentile 43 / cohort 524

Distance 21.34 pc · percentile 7 / cohort 572

ESI 0.527 · percentile 96 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

13.352 days

Semi-major axis

0.0820 AU

Eccentricity

0.370

Inclination

— °

Year Length

A year here lasts approximately 13.35 Earth days (3.7% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.0820 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.527

0 = alien, 1 = Earth-identical

Insufficient insolation data. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Nagel et al. 2019

Instrument

CARMENES

Publication

2019-02

Observation locale

Ground

Discovery cohort

Planets confirmed in 2019 at Calar Alto Observatory (4 shown).

Teegarden's Star b · Rocky Terrestrial Teegarden's Star c · Rocky Terrestrial LSPM J2116+0234 b · Sub-Neptune GJ 3512 b · Gas Giant

Host System: GJ 4276

Spectral Class

M-type red dwarf

Effective Temperature

3,387 K — cooler than the Sun (5,778 K)

Estimated Age

6.90 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.407 R☉

Stellar Mass

0.406 M☉

Metallicity [Fe/H]

0.12

Extended Stellar Properties

Surface gravity (log g)

4.970 dex

Stellar density

8.277 g/cm³

Rotational v·sin i

2.00 km/s

Rotation period

64.30 days

Metallicity ratio

[Fe/H]

Distance

21.34 parsec

Light-years 69.59 ly

V-band magnitude

12.90 mag

Voyager-speed travel 1,227,207 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

46.840 mas

Total Proper Motion

333.366 mas/yr

PM Right Ascension

122.37 mas/yr

PM Declination

-310.10 mas/yr

Galactic Cartesian (pc)

x = 0.466 · y = -0.204 · z = 0.861

Equatorial (J2000)

RA 336.32215° · Dec 59.41250°

Galactic ℓ, b

105.290° · 1.643°

Ecliptic λ, β

18.387° · 60.587°

HTM-20 index

1728312683