Key parameters at a glance

A radius of 13.30 Earth radii
A mass of 708.76 Earth masses
Surface gravity around 4.01 g
An orbital period of 431.880 days
Semi-major axis 1.1700 AU
Distance from Earth 265.42 light-years
Earth Similarity Index 0.375
Travel time at Voyager 1 speed 4,680,754 years

1 sibling around HD 4203

HD 4203 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 4203 b this	Gas Giant	13.30	708.76	431.880	—	2001
HD 4203 c	Gas Giant	13.30	689.66	6,700.000	—	2014

HD 4203 b Planet Profile

Physical Specs

Radius

13.30 R⊕

Radius (Jupiter)

1.190 R♃

Mass

708.76 M⊕

Mass (Jupiter)

2.230 M♃

Density

1.66 g/cm³

Surface Gravity

4.01 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.375

HZ Position Unknown

Controversial No

Discovery

Year 2001

Method Radial Velocity

Facility W. M. Keck Observatory

Telescope 10 m Keck I Telescope

Size rank in cohort

Rank by radius

#793of 1771

top 44.7%

This planet

13.30R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

HD 12661 b 13.30 R⊕ HD 129445 b 13.30 R⊕ GJ 876 b 13.30 R⊕

Metric	Earth	HD 4203 b	Jupiter
Radius (R⊕)	1.00	13.30	11.21
Mass (M⊕)	1.00	708.76	317.83
Density (g/cm³)	5.51	1.66	1.33
Surface Gravity (g)	1.00	4.01	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	708.761 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 4203

HIP

HIP 3502

TIC

TIC 434225151

Gaia DR2

Gaia DR2 2801366000472903040

Gaia DR3

Gaia DR3 2801366000472903040

System

HD 4203

Percentile among Gas Giant cohort

Radius 13.300 R⊕ · percentile 53 / cohort 1771

Mass 708.761 M⊕ · percentile 58 / cohort 1747

Orbital period 431.88 d · percentile 65 / cohort 1533

Distance 81.38 pc · percentile 31 / cohort 1759

ESI 0.375 · percentile 78 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

431.880 days

Semi-major axis

1.1700 AU

Eccentricity

0.520

Inclination

— °

Year Length

A year here lasts about 1.18 Earth years on a highly eccentric trajectory at a mean orbital distance of 1.1700 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

60.300 m/s

Transit mid-time (BJD)

2,440,618.8000

Long. of periastron (ω)

-28.90°

Angular separation (arcsec)

14.40000

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.375

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Vogt et al. 2002

Instrument

HIRES Spectrometer

Publication

2002-03

Observation locale

Ground

Discovery cohort

Planets confirmed in 2001 at W. M. Keck Observatory (3 shown).

HD 178911 B b · Gas Giant HD 114783 b · Gas Giant HD 4208 b · Gas Giant

Host System: HD 4203

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,596 K — cooler than the Sun (5,778 K)

Estimated Age

8.52 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.420 R☉

Stellar Mass

1.250 M☉

Metallicity [Fe/H]

0.40

Extended Stellar Properties

Surface gravity (log g)

4.230 dex

Stellar density

0.415 g/cm³

Systemic radial velocity

-14.06 km/s

Rotational v·sin i

1.23 km/s

Activity index (log R'HK)

-5.180

Metallicity ratio

[Fe/H]

Distance

81.38 parsec

Light-years 265.42 ly

V-band magnitude

8.70 mag

Voyager-speed travel 4,680,754 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

12.260 mas

Total Proper Motion

174.140 mas/yr

PM Right Ascension

122.07 mas/yr

PM Declination

-124.19 mas/yr

Galactic Cartesian (pc)

x = 0.919 · y = 0.182 · z = 0.349

Equatorial (J2000)

RA 11.17223° · Dec 20.44839°

Galactic ℓ, b

120.791° · -42.395°

Ecliptic λ, β

18.382° · 14.378°

HTM-20 index

-1327445277

Observation Record

Photometric series

RV measurements

Stellar spectra

Archive notes