Key parameters at a glance

A radius of 2.40 Earth radii
A mass of 4.20 Earth masses
Surface gravity around 0.73 g
An orbital period of 138.073 days
Semi-major axis 0.5300 AU
Equilibrium temperature 411 K (138 °C)
Distance from Earth 344.03 light-years
Earth Similarity Index 0.564
Travel time at Voyager 1 speed 6,066,957 years

2 siblings around HD 224018

HD 224018 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 224018 b	Rocky Terrestrial	0.91	4.10	10.641	968	2025
HD 224018 c	Sub-Neptune	2.42	10.40	36.577	641	2025
HD 224018 d this	Sub-Neptune	2.40	4.20	138.073	411	2025

HD 224018 d Planet Profile

Physical Specs

Radius

2.40 R⊕

Radius (Jupiter)

0.214 R♃

Mass

4.20 M⊕

Mass (Jupiter)

0.013 M♃

Density

1.70 g/cm³

Surface Gravity

0.73 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.564

HZ Position Unknown

Controversial No

Discovery

Year 2025

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#1333of 1978

top 67.3%

This planet

2.40R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-194 d 2.40 R⊕ KIC 8540376 c 2.40 R⊕ Kepler-112 c 2.40 R⊕

Metric	Earth	HD 224018 d	Jupiter
Radius (R⊕)	1.00	2.40	11.21
Mass (M⊕)	1.00	4.20	317.83
Density (g/cm³)	5.51	1.70	1.33
Surface Gravity (g)	1.00	0.73	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	4.200 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

HD 224018

TIC

TIC 248608315

Gaia DR2

Gaia DR2 2446440348493043968

Gaia DR3

Gaia DR3 2446440348493043968

System

HD 224018

Percentile among Sub-Neptune cohort

Radius 2.400 R⊕ · percentile 32 / cohort 1978

Mass 4.200 M⊕ · percentile 2 / cohort 1978

Orbital period 138.07 d · percentile 96 / cohort 1946

Distance 105.48 pc · percentile 20 / cohort 1975

ESI 0.564 · percentile 78 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

138.073 days

Semi-major axis

0.5300 AU

Eccentricity

0.040

Inclination

89.90 °

Year Length

A year here lasts approximately 138.07 Earth days (37.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.5300 AU.

Transit Fingerprint

Rp / R★

0.019270

Transit midpoint (BJD)

2,457,741.7450

Extended Orbital Architecture

Planet / star radius ratio

0.019270

RV semi-amplitude (K)

0.520 m/s

Transit mid-time (BJD)

2,457,741.7450

Long. of periastron (ω)

206.00°

Angular separation (arcsec)

5.02000

Eq. Temperature

411K

(138 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.564

0 = alien, 1 = Earth-identical

Insufficient insolation data — the surface is too hot to retain surface water.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Discovery Paper

Primary reference

Damasso et al. 2025

Instrument

Kepler CCD Array

Publication

2025-08

Observation locale

Space

Host System: HD 224018

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,784 K — hotter than the Sun (5,778 K)

Estimated Age

7.00 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.147 R☉

Stellar Mass

1.013 M☉

Metallicity [Fe/H]

0.05

Extended Stellar Properties

Surface gravity (log g)

4.320 dex

Stellar density

0.902 g/cm³

Systemic radial velocity

-62.77 km/s

Rotational v·sin i

2.10 km/s

Metallicity ratio

[Fe/H]

Distance

105.48 parsec

Light-years 344.03 ly

V-band magnitude

9.72 mag

Voyager-speed travel 6,066,957 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

9.452 mas

Total Proper Motion

112.877 mas/yr

PM Right Ascension

-112.58 mas/yr

PM Declination

-8.19 mas/yr

Galactic Cartesian (pc)

x = 0.996 · y = -0.024 · z = -0.082

Equatorial (J2000)

RA 358.63901° · Dec -4.72334°

Galactic ℓ, b

89.242° · -63.810°

Ecliptic λ, β

356.867° · -3.792°

HTM-20 index

1167457204