Key parameters at a glance

A radius of 6.67 Earth radii
A mass of 36.00 Earth masses
Surface gravity around 0.81 g
An orbital period of 7,600.000 days
Semi-major axis 5.4000 AU
Distance from Earth 11.62 light-years
Earth Similarity Index 0.398
Travel time at Voyager 1 speed 204,894 years

GJ 15 A c Planet Profile

Physical Specs

Radius

6.67 R⊕

Radius (Jupiter)

0.595 R♃

Mass

36.00 M⊕

Mass (Jupiter)

0.113 M♃

Density

0.67 g/cm³

Surface Gravity

0.81 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.398

HZ Position Unknown

Controversial No

Discovery

Year 2018

Method Radial Velocity

Facility Roque de los Muchachos Observatory

Telescope 3.58 m Telescopio Nazionale Galileo

Size rank in cohort

Rank by radius

#226of 574

top 39.2%

This planet

6.67R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

Kepler-139 f 6.67 R⊕ Kepler-767 b 6.64 R⊕ K2-45 b 6.71 R⊕

Metric	Earth	GJ 15 A c	Jupiter
Radius (R⊕)	1.00	6.67	11.21
Mass (M⊕)	1.00	36.00	317.83
Density (g/cm³)	5.51	0.67	1.33
Surface Gravity (g)	1.00	0.81	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	36.000 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 1326

HIP

HIP 1475

TIC

TIC 440109725

Gaia DR2

Gaia DR2 385334230892516480

Gaia DR3

Gaia DR3 385334230892516480

System

GJ 15

Percentile among Neptune-like cohort

Radius 6.670 R⊕ · percentile 60 / cohort 574

Mass 36.000 M⊕ · percentile 58 / cohort 574

Orbital period 7,600.00 d · percentile 100 / cohort 524

Distance 3.56 pc · percentile 0 / cohort 572

ESI 0.398 · percentile 73 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

7,600.000 days

Semi-major axis

5.4000 AU

Eccentricity

0.270

Inclination

— °

Year Length

A year here lasts about 20.81 Earth years on a mildly elliptical path at a mean orbital distance of 5.4000 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.398

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Pinamonti et al. 2018

Instrument

HARPS-N Spectrograph

Publication

2018-09

Observation locale

Ground

Discovery cohort

Planets confirmed in 2018 at Roque de los Muchachos Observatory (3 shown).

Gl 686 b · Sub-Neptune HD 233832 b · Gas Giant HD 220197 b · Neptune-like

Host System: GJ 15 A

Spectral Class

M-type red dwarf

Effective Temperature

3,607 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.380 R☉

Stellar Mass

0.380 M☉

Metallicity [Fe/H]

-0.34

Extended Stellar Properties

Surface gravity (log g)

4.870 dex

Stellar density

8.374 g/cm³

Systemic radial velocity

11.30 km/s

Rotational v·sin i

1.09 km/s

Metallicity ratio

[Fe/H]

Distance

3.56 parsec

Light-years 11.62 ly

V-band magnitude

8.09 mag

Voyager-speed travel 204,894 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

280.690 mas

Total Proper Motion

2,920.711 mas/yr

PM Right Ascension

2,891.52 mas/yr

PM Declination

411.90 mas/yr

Galactic Cartesian (pc)

x = 0.717 · y = 0.058 · z = 0.695

Equatorial (J2000)

RA 4.61267° · Dec 44.02473°

Galactic ℓ, b

116.690° · -18.447°

Ecliptic λ, β

24.686° · 37.924°

HTM-20 index

-379120508

Observation Record

Photometric series

Stellar spectra

Archive notes