Key parameters at a glance
- A radius of 2.06 Earth radii
- A mass of 4.91 Earth masses
- Surface gravity around 1.16 g
- An orbital period of 11.681 days
- Semi-major axis 0.1000 AU
- Equilibrium temperature 945 K (672 °C)
- Distance from Earth 142.35 light-years
- Earth Similarity Index 0.286
- Travel time at Voyager 1 speed 2,510,385 years
2 siblings around HD 28471
HD 28471 d shares its host star with 2 other confirmed planets. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| HD 28471 b | Super-Earth | 1.75 | 3.72 | 3.165 | 1,377 | 2025 |
| HD 28471 c | Sub-Neptune | 2.26 | 5.72 | 6.125 | 1,066 | 2025 |
| HD 28471 d this | Sub-Neptune | 2.06 | 4.91 | 11.681 | 945 | 2025 |
HD 28471 d Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1875of 1978
top 94.7%
This planet
2.06R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | HD 28471 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.06 | 11.21 |
| Mass (M⊕) | 1.00 | 4.91 | 317.83 |
| Density (g/cm³) | 5.51 | 3.09 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.16 | 2.53 |
| Insolation (S⊕) | 1.00 | — | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 4.910 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 28471
HIP
HIP 20625
TIC
TIC 38698692
Gaia DR2
Gaia DR2 4675222436007028608
Gaia DR3
Gaia DR3 4675222436007028608
System
HD 28471
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 11.68 Earth days (3.2% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1000 AU.
Extended Orbital Architecture
RV semi-amplitude (K)
1.411 m/s
Transit mid-time (BJD)
2,452,945.8060
Long. of periastron (ω)
96.00°
Angular separation (arcsec)
2.29000
Eq. Temperature
945K
(672 °C)
Insolation (S⊕)
—
Earth = 1.00
Earth Similarity (ESI)
0.286
0 = alien, 1 = Earth-identical
Insufficient insolation data — the surface is too hot to retain surface water.
Discovery Paper
Primary reference
Stevenson et al. 2025Instrument
HARPS Spectrograph
Publication
2025-08
Observation locale
Ground
Discovery cohort
Planets confirmed in 2025 at La Silla Observatory (12 shown).
Host System: HD 28471
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,766 K — cooler than the Sun (5,778 K)
Estimated Age
6.56 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
1.080 R☉
Stellar Mass
0.980 M☉
Metallicity [Fe/H]
-0.04
Extended Stellar Properties
Surface gravity (log g)
4.380 dex
Stellar density
1.121 g/cm³
Rotational v·sin i
2.00 km/s
Rotation period
26.18 days
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 7 bands
Astrometric Data
Parallax
22.883 mas
Total Proper Motion
327.547 mas/yr
PM Right Ascension
-62.27 mas/yr
PM Declination
321.57 mas/yr
Galactic Cartesian (pc)
x = 0.176 · y = 0.400 · z = -0.899
Equatorial (J2000)
RA 66.28752° · Dec -64.07869°
Galactic ℓ, b
275.683° · -39.935°
Ecliptic λ, β
3.072° · -79.860°
HTM-20 index
643723563
Similar Worlds
Kepler-183 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.06 R⊕ · 3,426.7 ly
Kepler-832 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.06 R⊕ · 5,505.9 ly
Kepler-1615 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.06 R⊕ · 4,546.1 ly
Kepler-958 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.06 R⊕ · 1,467.0 ly
Kepler-377 c
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.06 R⊕ · 2,686.9 ly
Kepler-449 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.06 R⊕ · 789.1 ly