Key parameters at a glance

A radius of 4.04 Earth radii
A mass of 15.40 Earth masses
Surface gravity around 0.94 g
An orbital period of 11.094 days
Semi-major axis 0.1010 AU
Equilibrium temperature 835 K (562 °C)
Distance from Earth 5,363.99 light-years
Earth Similarity Index 0.249
Travel time at Voyager 1 speed 94,594,032 years

2 siblings around Kepler-228

Kepler-228 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
Kepler-228 b	Super-Earth	1.53	2.96	2.567	1,360	2014
Kepler-228 c	Sub-Neptune	2.70	7.75	4.134	1,160	2014
Kepler-228 d this	Neptune-like	4.04	15.40	11.094	835	2014

Kepler-228 d Planet Profile

Physical Specs

Radius

4.04 R⊕

Radius (Jupiter)

0.360 R♃

Mass

15.40 M⊕

Mass (Jupiter)

0.048 M♃

Density

1.28 g/cm³

Surface Gravity

0.94 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.249

HZ Position Inner

Controversial No

Discovery

Year 2014

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#561of 574

top 97.6%

This planet

4.04R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

BD-11 4672 c 4.04 R⊕ K2-7 b 4.04 R⊕ TOI-4495 c 4.03 R⊕

Metric	Earth	Kepler-228 d	Jupiter
Radius (R⊕)	1.00	4.04	11.21
Mass (M⊕)	1.00	15.40	317.83
Density (g/cm³)	5.51	1.28	1.33
Surface Gravity (g)	1.00	0.94	2.53
Insolation (S⊕)	1.00	122.78	0.037

Star Catalogue Identifiers

TIC

TIC 27772524

Gaia DR2

Gaia DR2 2086660283961964416

Gaia DR3

Gaia DR3 2086660283961964416

System

Kepler-228

Percentile among Neptune-like cohort

Radius 4.040 R⊕ · percentile 2 / cohort 574

Mass 15.400 M⊕ · percentile 8 / cohort 574

Orbital period 11.09 d · percentile 39 / cohort 524

Distance 1,644.61 pc · percentile 86 / cohort 572

ESI 0.249 · percentile 40 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

11.094 days

Semi-major axis

0.1010 AU

Eccentricity

0.000

Inclination

88.11 °

Year Length

A year here lasts approximately 11.09 Earth days (3.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1010 AU.

Transit Fingerprint

Depth

0.152 %

Duration

4.591 h

Impact parameter b

0.460

Rp / R★

0.040340

Transit midpoint (BJD)

2,455,004.2012

Photometric dip

Transit produces a flux drop of 1,518 ppm lasting ≈ 4.59 h.

Extended Orbital Architecture

Planet / star radius ratio

0.040340

Semi-major axis / stellar radius

10.900

Impact parameter (b)

0.460

Transit mid-time (BJD)

2,455,004.2012

Angular separation (arcsec)

0.06140

Eq. Temperature

835K

(562 °C)

Insolation (S⊕)

122.78

Earth = 1.00

Earth Similarity (ESI)

0.249

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.

Discovery Paper

Primary reference

Rowe et al. 2014

Instrument

Kepler CCD Array

Publication

2014-03

Observation locale

Space

Discovery cohort

Planets confirmed in 2014 at Kepler (12 shown).

Kepler-186 e · Super-Earth Kepler-395 c · Super-Earth Kepler-220 e · Super-Earth Kepler-249 d · Super-Earth Kepler-296 f · Super-Earth Kepler-367 c · Rocky Terrestrial Kepler-296 e · Super-Earth Kepler-155 c · Sub-Neptune Kepler-138 d · Super-Earth Kepler-333 c · Rocky Terrestrial Kepler-331 d · Super-Earth Kepler-267 d · Sub-Neptune

Host System: Kepler-228

Spectral Class

F-type yellow-white

Effective Temperature

6,043 K — hotter than the Sun (5,778 K)

Estimated Age

6.76 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.014 R☉

Stellar Mass

1.006 M☉

Metallicity [Fe/H]

0.18

Extended Stellar Properties

Surface gravity (log g)

4.467 dex

Stellar density

0.790 g/cm³

Metallicity ratio

[Fe/H]

Distance

1,644.61 parsec

Light-years 5,363.99 ly

V-band magnitude

15.90 mag

Voyager-speed travel 94,594,032 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.580 mas

Total Proper Motion

9.434 mas/yr

PM Right Ascension

-5.05 mas/yr

PM Declination

-7.97 mas/yr

Galactic Cartesian (pc)

x = 0.295 · y = -0.597 · z = 0.746

Equatorial (J2000)

RA 296.28609° · Dec 48.22463°

Galactic ℓ, b

81.503° · 11.676°

Ecliptic λ, β

319.563° · 67.194°

HTM-20 index

1987710185