Key parameters at a glance

A radius of 3.43 Earth radii
A mass of 11.66 Earth masses
Surface gravity around 0.99 g
An orbital period of 11.848 days
Semi-major axis 0.0974 AU
Distance from Earth 136.44 light-years
Earth Similarity Index 0.595
Travel time at Voyager 1 speed 2,406,054 years

1 sibling around HD 20003

HD 20003 b shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
HD 20003 b this	Sub-Neptune	3.43	11.66	11.848	—	2019
HD 20003 c	Sub-Neptune	3.89	14.44	33.924	—	2019

HD 20003 b Planet Profile

Physical Specs

Radius

3.43 R⊕

Radius (Jupiter)

0.306 R♃

Mass

11.66 M⊕

Mass (Jupiter)

0.037 M♃

Density

1.59 g/cm³

Surface Gravity

0.99 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.595

HZ Position Unknown

Controversial No

Discovery

Year 2019

Method Radial Velocity

Facility La Silla Observatory

Telescope 3.6 m ESO Telescope

Size rank in cohort

Rank by radius

#205of 1978

top 10.3%

This planet

3.43R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-357 d 3.43 R⊕ TOI-5789 e 3.43 R⊕ Kepler-182 c 3.43 R⊕

Metric	Earth	HD 20003 b	Jupiter
Radius (R⊕)	1.00	3.43	11.21
Mass (M⊕)	1.00	11.66	317.83
Density (g/cm³)	5.51	1.59	1.33
Surface Gravity (g)	1.00	0.99	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	11.660 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 20003

HIP

HIP 14530

TIC

TIC 370137704

Gaia DR2

Gaia DR2 4642472794978268800

Gaia DR3

Gaia DR3 4642472794978268800

System

HD 20003

Percentile among Sub-Neptune cohort

Radius 3.430 R⊕ · percentile 89 / cohort 1978

Mass 11.660 M⊕ · percentile 83 / cohort 1978

Orbital period 11.85 d · percentile 41 / cohort 1946

Distance 41.83 pc · percentile 10 / cohort 1975

ESI 0.595 · percentile 82 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

11.848 days

Semi-major axis

0.0974 AU

Eccentricity

0.360

Inclination

— °

Year Length

A year here lasts approximately 11.85 Earth days (3.2% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.0974 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.595

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Udry et al. 2019

Instrument

HARPS Spectrograph

Publication

2019-02

Observation locale

Ground

Discovery cohort

Planets confirmed in 2019 at La Silla Observatory (12 shown).

HD 20781 b · Rocky Terrestrial HD 20781 c · Sub-Neptune HD 21693 b · Sub-Neptune HD 45184 c · Sub-Neptune HD 134060 b · Sub-Neptune HD 31527 b · Sub-Neptune HD 20781 d · Sub-Neptune HD 31527 d · Sub-Neptune HD 45184 b · Sub-Neptune HD 51608 b · Sub-Neptune HD 136352 d · Sub-Neptune HD 20781 e · Sub-Neptune

Host System: HD 20003

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,494 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.922 R☉

Stellar Mass

0.875 M☉

Metallicity [Fe/H]

0.04

Extended Stellar Properties

Surface gravity (log g)

4.410 dex

Stellar density

1.690 g/cm³

Systemic radial velocity

-16.17 km/s

Rotational v·sin i

1.90 km/s

Rotation period

38.90 days

Metallicity ratio

[Fe/H]

Distance

41.83 parsec

Light-years 136.44 ly

V-band magnitude

8.39 mag

Voyager-speed travel 2,406,054 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

23.876 mas

Total Proper Motion

72.337 mas/yr

PM Right Ascension

71.89 mas/yr

PM Declination

-8.00 mas/yr

Galactic Cartesian (pc)

x = 0.207 · y = 0.222 · z = -0.953

Equatorial (J2000)

RA 46.90901° · Dec -72.32192°

Galactic ℓ, b

289.877° · -41.176°

Ecliptic λ, β

319.761° · -74.232°

HTM-20 index

995228547