Key parameters at a glance

A radius of 3.77 Earth radii
A mass of 13.64 Earth masses
Surface gravity around 0.96 g
An orbital period of 19.466 days
Semi-major axis 0.1190 AU
Equilibrium temperature 401 K (128 °C)
Distance from Earth 50.74 light-years
Earth Similarity Index 0.506
Travel time at Voyager 1 speed 894,830 years
Almost certainly tidally locked to its host star given the close orbit

GJ 720 A b Planet Profile

Physical Specs

Radius

3.77 R⊕

Radius (Jupiter)

0.336 R♃

Mass

13.64 M⊕

Mass (Jupiter)

0.043 M♃

Density

1.40 g/cm³

Surface Gravity

0.96 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.506

HZ Position Unknown

Controversial No

Discovery

Year 2021

Method Radial Velocity

Facility Roque de los Muchachos Observatory

Telescope 3.58 m Telescopio Nazionale Galileo

Size rank in cohort

Rank by radius

#63of 1978

top 3.1%

This planet

3.77R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

K2-276 b 3.77 R⊕ HD 141004 b 3.77 R⊕ Kepler-315 b 3.77 R⊕

Metric	Earth	GJ 720 A b	Jupiter
Radius (R⊕)	1.00	3.77	11.21
Mass (M⊕)	1.00	13.64	317.83
Density (g/cm³)	5.51	1.40	1.33
Surface Gravity (g)	1.00	0.96	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	13.640 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HIP

HIP 91128

TIC

TIC 122958010

Gaia DR2

Gaia DR2 2118424350249708800

Gaia DR3

Gaia DR3 2118424350249708800

System

GJ 720

Percentile among Sub-Neptune cohort

Radius 3.770 R⊕ · percentile 97 / cohort 1978

Mass 13.640 M⊕ · percentile 90 / cohort 1978

Orbital period 19.47 d · percentile 61 / cohort 1946

Distance 15.56 pc · percentile 3 / cohort 1975

ESI 0.506 · percentile 71 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

19.466 days

Semi-major axis

0.1190 AU

Eccentricity

0.120

Inclination

— °

Year Length

A year here lasts approximately 19.47 Earth days (5.3% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1190 AU.

Eq. Temperature

401K

(128 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.506

0 = alien, 1 = Earth-identical

Insufficient insolation data — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Gonz Aacute Lez Aacute Lvarez et al. 2021

Instrument

HARPS-N Spectrograph

Publication

2021-05

Observation locale

Ground

Host System: GJ 720 A

Spectral Class

M-type red dwarf

Effective Temperature

3,837 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.560 R☉

Stellar Mass

0.570 M☉

Metallicity [Fe/H]

-0.14

Extended Stellar Properties

Surface gravity (log g)

4.710 dex

Stellar density

3.991 g/cm³

Rotational v·sin i

0.99 km/s

Rotation period

36.05 days

Metallicity ratio

[Fe/H]

Distance

15.56 parsec

Light-years 50.74 ly

V-band magnitude

9.84 mag

Voyager-speed travel 894,830 yr

Multi-band Host Photometry — 8 bands

Astrometric Data

Parallax

64.249 mas

Total Proper Motion

580.281 mas/yr

PM Right Ascension

452.19 mas/yr

PM Declination

363.67 mas/yr

Galactic Cartesian (pc)

x = 0.107 · y = -0.690 · z = 0.716

Equatorial (J2000)

RA 278.82942° · Dec 45.74560°

Galactic ℓ, b

74.396° · 21.731°

Ecliptic λ, β

287.115° · 68.661°

HTM-20 index

1560343352