Key parameters at a glance

A radius of 4.12 Earth radii
A mass of 15.89 Earth masses
Surface gravity around 0.94 g
An orbital period of 15.560 days
Semi-major axis 0.1200 AU
Distance from Earth 71.81 light-years
Earth Similarity Index 0.535
Travel time at Voyager 1 speed 1,266,296 years

HD 4308 b Planet Profile

Physical Specs

Radius

4.12 R⊕

Radius (Jupiter)

0.368 R♃

Mass

15.89 M⊕

Mass (Jupiter)

0.050 M♃

Density

1.25 g/cm³

Surface Gravity

0.94 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.535

HZ Position Unknown

Controversial No

Discovery

Year 2005

Method Radial Velocity

Facility La Silla Observatory

Telescope 3.6 m ESO Telescope

Size rank in cohort

Rank by radius

#542of 574

top 94.3%

This planet

4.12R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

HD 77338 b 4.12 R⊕ HD 156098 b 4.12 R⊕ Kepler-1799 b 4.13 R⊕

Metric	Earth	HD 4308 b	Jupiter
Radius (R⊕)	1.00	4.12	11.21
Mass (M⊕)	1.00	15.89	317.83
Density (g/cm³)	5.51	1.25	1.33
Surface Gravity (g)	1.00	0.94	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	15.892 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 4308

HIP

HIP 3497

TIC

TIC 234501204

Gaia DR2

Gaia DR2 4708607629114652032

Gaia DR3

Gaia DR3 4708607629114652032

System

HD 4308

Percentile among Neptune-like cohort

Radius 4.120 R⊕ · percentile 5 / cohort 574

Mass 15.892 M⊕ · percentile 11 / cohort 574

Orbital period 15.56 d · percentile 47 / cohort 524

Distance 22.02 pc · percentile 7 / cohort 572

ESI 0.535 · percentile 97 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

15.560 days

Semi-major axis

0.1200 AU

Eccentricity

0.000

Inclination

— °

Year Length

A year here lasts approximately 15.56 Earth days (4.3% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1200 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.535

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Udry et al. 2006

Instrument

HARPS Spectrograph

Publication

2006-02

Observation locale

Ground

Discovery cohort

Planets confirmed in 2005 at La Silla Observatory (10 shown).

GJ 581 b · Neptune-like HD 11977 b · Gas Giant HD 142022 A b · Gas Giant HD 102117 b · Neptune-like HD 101930 b · Gas Giant HD 27894 b · Gas Giant HD 212301 b · Gas Giant HD 93083 b · Gas Giant HD 63454 b · Gas Giant HD 2638 b · Gas Giant

Host System: HD 4308

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,686 K — cooler than the Sun (5,778 K)

Estimated Age

4.30 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.020 R☉

Stellar Mass

0.930 M☉

Metallicity [Fe/H]

-0.35

Extended Stellar Properties

Surface gravity (log g)

4.390 dex

Stellar density

1.239 g/cm³

Systemic radial velocity

95.19 km/s

Rotational v·sin i

1.20 km/s

Metallicity ratio

[Fe/H]

Distance

22.02 parsec

Light-years 71.81 ly

V-band magnitude

6.55 mag

Voyager-speed travel 1,266,296 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

45.393 mas

Total Proper Motion

758.140 mas/yr

PM Right Ascension

157.50 mas/yr

PM Declination

-741.60 mas/yr

Galactic Cartesian (pc)

x = 0.404 · y = 0.080 · z = -0.911

Equatorial (J2000)

RA 11.16526° · Dec -65.65272°

Galactic ℓ, b

304.053° · -51.461°

Ecliptic λ, β

324.435° · -60.185°

HTM-20 index

1158081559

Observation Record

Photometric series

RV measurements

Stellar spectra

Archive notes

Wikipedia → Image: Wikimedia Commons · Celestia · GPL