Key parameters at a glance
- A radius of 12.40 Earth radii
- A mass of 3,747.20 Earth masses
- Surface gravity around 24.37 g
- An orbital period of 5,103.000 days
- Semi-major axis 6.2800 AU
- Equilibrium temperature 146 K (-127 °C)
- Distance from Earth 300.91 light-years
- Earth Similarity Index 0.268
- Travel time at Voyager 1 speed 5,306,511 years
1 sibling around HD 118203
HD 118203 c 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 118203 b | Gas Giant | 12.78 | 680.15 | 6.135 | 1,361 | 2005 |
| HD 118203 c this | Gas Giant | 12.40 | 3,747.20 | 5,103.000 | 146 | 2024 |
HD 118203 c Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#1298of 1771
top 73.2%
This planet
12.40R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | HD 118203 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 12.40 | 11.21 |
| Mass (M⊕) | 1.00 | 3,747.20 | 317.83 |
| Density (g/cm³) | 5.51 | 10.80 | 1.33 |
| Surface Gravity (g) | 1.00 | 24.37 | 2.53 |
| Insolation (S⊕) | 1.00 | — | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 3,747.197 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
HD
HD 118203
HIP
HIP 66192
TIC
TIC 286923464
Gaia DR2
Gaia DR2 1560420854826284928
Gaia DR3
Gaia DR3 1560420854826284928
System
HD 118203
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts about 13.97 Earth years on a mildly elliptical path at a mean orbital distance of 6.2800 AU.
Extended Orbital Architecture
RV semi-amplitude (K)
118.000 m/s
Transit mid-time (BJD)
2,456,825.0000
Long. of periastron (ω)
175.00°
Angular separation (arcsec)
68.10000
Eq. Temperature
146K
(-127 °C)
Insolation (S⊕)
—
Earth = 1.00
Earth Similarity (ESI)
0.268
0 = alien, 1 = Earth-identical
Insufficient insolation data — any water would exist as deep ice.
Detection Signatures
Radial velocity
Stellar wobble has been measured spectroscopically.
Astrometry
Positional wobble of the host star was measured.
Discovery Paper
Primary reference
Maciejewski et al. 2024Instrument
Multiple Instruments
Publication
2024-07
Observation locale
Ground
Discovery cohort
Planets confirmed in 2024 at Multiple Observatories (12 shown).
Host System: HD 118203
Spectral Class
K-type orange
Effective Temperature
5,742 K — cooler than the Sun (5,778 K)
Estimated Age
4.73 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
2.040 R☉
Stellar Mass
1.270 M☉
Metallicity [Fe/H]
0.29
Extended Stellar Properties
Surface gravity (log g)
3.920 dex
Stellar density
0.196 g/cm³
Systemic radial velocity
-29.36 km/s
Rotational v·sin i
5.89 km/s
Rotation period
23.10 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
10.810 mas
Total Proper Motion
116.628 mas/yr
PM Right Ascension
-85.88 mas/yr
PM Declination
-78.91 mas/yr
Galactic Cartesian (pc)
x = -0.543 · y = -0.236 · z = 0.806
Equatorial (J2000)
RA 203.50996° · Dec 53.72819°
Galactic ℓ, b
109.345° · 62.262°
Ecliptic λ, β
169.127° · 56.467°
HTM-20 index
814331595
Observation Record
Photometric series
1
RV measurements
1
Archive notes
1
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