Key parameters at a glance

A radius of 4.57 Earth radii
A mass of 13.90 Earth masses
Surface gravity around 0.67 g
An orbital period of 3.337 days
Semi-major axis 0.0355 AU
Equilibrium temperature 594 K (320 °C)
Distance from Earth 95.96 light-years
Earth Similarity Index 0.313
Travel time at Voyager 1 speed 1,692,249 years
Almost certainly tidally locked to its host star given the close orbit

GJ 3470 b Planet Profile

Physical Specs

Radius

4.57 R⊕

Radius (Jupiter)

0.408 R♃

Mass

13.90 M⊕

Mass (Jupiter)

0.044 M♃

Density

0.80 g/cm³

Surface Gravity

0.67 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.313

HZ Position Inner

Controversial No

Discovery

Year 2012

Method Radial Velocity

Facility La Silla Observatory

Telescope 3.6 m ESO Telescope

Size rank in cohort

Rank by radius

#453of 574

top 78.7%

This planet

4.57R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

Kepler-740 b 4.57 R⊕ K2-405 b 4.57 R⊕ Kepler-1656 b 4.57 R⊕

Metric	Earth	GJ 3470 b	Jupiter
Radius (R⊕)	1.00	4.57	11.21
Mass (M⊕)	1.00	13.90	317.83
Density (g/cm³)	5.51	0.80	1.33
Surface Gravity (g)	1.00	0.67	2.53
Insolation (S⊕)	1.00	29.66	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	13.900 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 19028197

Gaia DR2

Gaia DR2 654687847820642560

Gaia DR3

Gaia DR3 654687847820642560

System

GJ 3470

Percentile among Neptune-like cohort

Radius 4.570 R⊕ · percentile 21 / cohort 574

Mass 13.900 M⊕ · percentile 5 / cohort 574

Orbital period 3.34 d · percentile 6 / cohort 524

Distance 29.42 pc · percentile 9 / cohort 572

ESI 0.313 · percentile 53 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

3.337 days

Semi-major axis

0.0355 AU

Eccentricity

0.017

Inclination

89.13 °

Year Length

A year here lasts approximately 3.34 Earth days (0.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0355 AU.

Transit Fingerprint

Depth

0.677 %

Duration

1.898 h

Impact parameter b

0.400

Rp / R★

0.076420

Transit midpoint (BJD)

2,455,983.7042

Photometric dip

Transit produces a flux drop of 6,766 ppm lasting ≈ 1.90 h.

Extended Orbital Architecture

Planet / star radius ratio

0.076420

Semi-major axis / stellar radius

13.980

Impact parameter (b)

0.400

RV semi-amplitude (K)

13.400 m/s

Transit mid-time (BJD)

2,455,983.7042

Long. of periastron (ω)

1.70°

Angular separation (arcsec)

1.21000

Eq. Temperature

594K

(320 °C)

Insolation (S⊕)

29.66

Earth = 1.00

Earth Similarity (ESI)

0.313

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Discovery Paper

Primary reference

Bonfils et al. 2012

Instrument

HARPS Spectrograph

Publication

2012-10

Observation locale

Ground

Discovery cohort

Planets confirmed in 2012 at La Silla Observatory (11 shown).

GJ 676 A d · Super-Earth GJ 667 C b · Sub-Neptune GJ 676 A e · Sub-Neptune HD 77338 b · Neptune-like HD 166724 b · Gas Giant HD 219077 b · Gas Giant HD 98649 b · Gas Giant HD 196067 b · Gas Giant HD 27631 b · Gas Giant HD 220689 b · Gas Giant HD 106515 A b · Gas Giant

Host System: GJ 3470

Spectral Class

M-type red dwarf

Effective Temperature

3,600 K — cooler than the Sun (5,778 K)

Estimated Age

1.65 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.547 R☉

Stellar Mass

0.539 M☉

Metallicity [Fe/H]

0.20

Extended Stellar Properties

Surface gravity (log g)

4.695 dex

Stellar density

3.300 g/cm³

Systemic radial velocity

26.52 km/s

Rotation period

21.54 days

Metallicity ratio

[Fe/H]

Distance

29.42 parsec

Light-years 95.96 ly

V-band magnitude

12.33 mag

Voyager-speed travel 1,692,249 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

33.960 mas

Total Proper Motion

194.361 mas/yr

PM Right Ascension

-185.73 mas/yr

PM Declination

-57.26 mas/yr

Galactic Cartesian (pc)

x = -0.479 · y = 0.837 · z = 0.265

Equatorial (J2000)

RA 119.77350° · Dec 15.39121°

Galactic ℓ, b

206.235° · 21.757°

Ecliptic λ, β

118.726° · -5.128°

HTM-20 index

-338082220

Observation Record

RV measurements

Transmission spectra

Emission spectra

Archive notes