Key parameters at a glance

A radius of 2.10 Earth radii
A mass of 0.98 Earth masses
Surface gravity around 0.22 g
An orbital period of 8.011 days
Semi-major axis 0.0619 AU
Equilibrium temperature 453 K (180 °C)
Distance from Earth 886.17 light-years
Earth Similarity Index 0.436
Travel time at Voyager 1 speed 15,627,591 years
Almost certainly tidally locked to its host star given the close orbit

2 siblings around Kepler-54

Kepler-54 b 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-54 b this	Sub-Neptune	2.10	0.98	8.011	453	2012
Kepler-54 c	Rocky Terrestrial	1.23	0.70	12.072	395	2012
Kepler-54 d	Super-Earth	1.53	12.09	20.996	328	2014

Kepler-54 b Planet Profile

Physical Specs

Radius

2.10 R⊕

Radius (Jupiter)

0.187 R♃

Mass

0.98 M⊕

Mass (Jupiter)

0.003 M♃

Density

0.76 g/cm³

Surface Gravity

0.22 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.436

HZ Position Inner

Controversial No

Discovery

Year 2012

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#1818of 1978

top 91.9%

This planet

2.10R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

TOI-5734 b 2.10 R⊕ Kepler-52 b 2.10 R⊕ Kepler-360 c 2.10 R⊕

Metric	Earth	Kepler-54 b	Jupiter
Radius (R⊕)	1.00	2.10	11.21
Mass (M⊕)	1.00	0.98	317.83
Density (g/cm³)	5.51	0.76	1.33
Surface Gravity (g)	1.00	0.22	2.53
Insolation (S⊕)	1.00	12.36	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	0.980 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 271262203

Gaia DR2

Gaia DR2 2077974687557384704

Gaia DR3

Gaia DR3 2077974687557384704

System

Kepler-54

Percentile among Sub-Neptune cohort

Radius 2.100 R⊕ · percentile 7 / cohort 1978

Mass 0.980 M⊕ · percentile 0 / cohort 1978

Orbital period 8.01 d · percentile 26 / cohort 1946

Distance 271.70 pc · percentile 33 / cohort 1975

ESI 0.436 · percentile 60 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

8.011 days

Semi-major axis

0.0619 AU

Eccentricity

0.022

Inclination

89.59 °

Year Length

A year here lasts approximately 8.01 Earth days (2.2% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0619 AU.

Transit Fingerprint

Depth

0.133 %

Duration

3.413 h

Impact parameter b

0.946

Rp / R★

0.038420

Transit midpoint (BJD)

2,455,003.2057

Photometric dip

Transit produces a flux drop of 1,334 ppm lasting ≈ 3.41 h.

Extended Orbital Architecture

Planet / star radius ratio

0.038420

Semi-major axis / stellar radius

7.660

Impact parameter (b)

0.946

Transit mid-time (BJD)

2,455,003.2057

Angular separation (arcsec)

0.22800

Eq. Temperature

453K

(180 °C)

Insolation (S⊕)

12.36

Earth = 1.00

Earth Similarity (ESI)

0.436

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Detection Signatures

Transit photometry

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

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Steffen et al. 2013

Instrument

Kepler CCD Array

Publication

2013-01

Observation locale

Space

Discovery cohort

Planets confirmed in 2012 at Kepler (12 shown).

Kepler-54 c · Rocky Terrestrial Kepler-49 c · Sub-Neptune Kepler-55 b · Sub-Neptune Kepler-49 b · Sub-Neptune Kepler-81 c · Sub-Neptune Kepler-55 c · Sub-Neptune Kepler-52 c · Super-Earth Kepler-83 c · Sub-Neptune Kepler-32 d · Sub-Neptune Kepler-83 b · Sub-Neptune Kepler-80 c · Sub-Neptune Kepler-81 b · Sub-Neptune

Host System: Kepler-54

Spectral Class

M-type red dwarf

Effective Temperature

3,705 K — cooler than the Sun (5,778 K)

Estimated Age

4.83 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.500 R☉

Stellar Mass

0.510 M☉

Metallicity [Fe/H]

-0.27

Extended Stellar Properties

Surface gravity (log g)

4.750 dex

Stellar density

0.180 g/cm³

Metallicity ratio

[Fe/H]

Distance

271.70 parsec

Light-years 886.17 ly

V-band magnitude

16.28 mag

Voyager-speed travel 15,627,591 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

3.652 mas

Total Proper Motion

18.499 mas/yr

PM Right Ascension

0.03 mas/yr

PM Declination

-18.50 mas/yr

Galactic Cartesian (pc)

x = 0.306 · y = -0.663 · z = 0.683

Equatorial (J2000)

RA 294.77392° · Dec 43.05620°

Galactic ℓ, b

76.345° · 10.198°

Ecliptic λ, β

312.243° · 62.908°

HTM-20 index

-1445206968