Key parameters at a glance

A radius of 3.07 Earth radii
A mass of 9.65 Earth masses
Surface gravity around 1.02 g
An orbital period of 18.270 days
Semi-major axis 0.1139 AU
Equilibrium temperature 453 K (180 °C)
Distance from Earth 99.87 light-years
Earth Similarity Index 0.499
Travel time at Voyager 1 speed 1,761,206 years
Almost certainly tidally locked to its host star given the close orbit

GJ 9689 b Planet Profile

Physical Specs

Radius

3.07 R⊕

Radius (Jupiter)

0.274 R♃

Mass

9.65 M⊕

Mass (Jupiter)

0.030 M♃

Density

1.83 g/cm³

Surface Gravity

1.02 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.499

HZ Position Unknown

Controversial No

Discovery

Year 2020

Method Radial Velocity

Facility Roque de los Muchachos Observatory

Telescope 3.58 m Telescopio Nazionale Galileo

Size rank in cohort

Rank by radius

#456of 1978

top 23.0%

This planet

3.07R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-346 c 3.07 R⊕ Kepler-335 c 3.07 R⊕ Kepler-293 b 3.07 R⊕

Metric	Earth	GJ 9689 b	Jupiter
Radius (R⊕)	1.00	3.07	11.21
Mass (M⊕)	1.00	9.65	317.83
Density (g/cm³)	5.51	1.83	1.33
Surface Gravity (g)	1.00	1.02	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	9.650 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HIP

HIP 99699

TIC

TIC 87942223

Gaia DR2

Gaia DR2 1803475188714186368

Gaia DR3

Gaia DR3 1803475188714186368

System

GJ 9689

Percentile among Sub-Neptune cohort

Radius 3.070 R⊕ · percentile 77 / cohort 1978

Mass 9.650 M⊕ · percentile 70 / cohort 1978

Orbital period 18.27 d · percentile 59 / cohort 1946

Distance 30.62 pc · percentile 7 / cohort 1975

ESI 0.499 · percentile 70 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

18.270 days

Semi-major axis

0.1139 AU

Eccentricity

0.290

Inclination

— °

Year Length

A year here lasts approximately 18.27 Earth days (5.0% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1139 AU.

Eq. Temperature

453K

(180 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.499

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

Maldonado et al. 2021

Instrument

HARPS-N Spectrograph

Publication

2021-07

Observation locale

Ground

Discovery cohort

Planets confirmed in 2020 at Roque de los Muchachos Observatory (2 shown).

HD 164922 d · Super-Earth BD-11 4672 c · Neptune-like

Host System: GJ 9689

Spectral Class

M-type red dwarf

Effective Temperature

3,836 K — cooler than the Sun (5,778 K)

Estimated Age

8.90 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.570 R☉

Stellar Mass

0.590 M☉

Metallicity [Fe/H]

0.05

Extended Stellar Properties

Surface gravity (log g)

4.690 dex

Stellar density

3.776 g/cm³

Rotational v·sin i

1.47 km/s

Rotation period

39.97 days

Metallicity ratio

[Fe/H]

Distance

30.62 parsec

Light-years 99.87 ly

V-band magnitude

11.30 mag

Voyager-speed travel 1,761,206 yr

Multi-band Host Photometry — 7 bands

Astrometric Data

Parallax

32.629 mas

Total Proper Motion

422.357 mas/yr

PM Right Ascension

421.92 mas/yr

PM Declination

19.18 mas/yr

Galactic Cartesian (pc)

x = 0.536 · y = -0.812 · z = 0.232

Equatorial (J2000)

RA 303.46773° · Dec 13.38889°

Galactic ℓ, b

54.624° · -11.487°

Ecliptic λ, β

309.425° · 32.361°

HTM-20 index

-729215161