Key parameters at a glance

A radius of 2.21 Earth radii
A mass of 69.80 Earth masses
Surface gravity around 14.29 g
An orbital period of 42.152 days
Semi-major axis 0.2095 AU
Equilibrium temperature 349 K (76 °C)
Distance from Earth 1,887.78 light-years
Earth Similarity Index 0.464
Travel time at Voyager 1 speed 33,290,961 years
Almost certainly tidally locked to its host star given the close orbit

4 siblings around Kepler-55

Kepler-55 c shares its host star with 4 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-55 d	Super-Earth	1.59	3.15	2.211	931	2014
Kepler-55 e	Super-Earth	1.55	3.02	4.618	728	2014
Kepler-55 f	Super-Earth	1.59	3.15	10.199	559	2014
Kepler-55 b	Sub-Neptune	2.43	43.00	27.948	400	2012
Kepler-55 c this	Sub-Neptune	2.21	69.80	42.152	349	2012

Kepler-55 c Planet Profile

Physical Specs

Radius

2.21 R⊕

Radius (Jupiter)

0.197 R♃

Mass

69.80 M⊕

Mass (Jupiter)

0.220 M♃

Density

35.50 g/cm³

Surface Gravity

14.29 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.464

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

#1658of 1978

top 83.8%

This planet

2.21R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

K2-335 b 2.21 R⊕ OGLE-2005-BLG-390L b 2.21 R⊕ K2-275 c 2.21 R⊕

Metric	Earth	Kepler-55 c	Jupiter
Radius (R⊕)	1.00	2.21	11.21
Mass (M⊕)	1.00	69.80	317.83
Density (g/cm³)	5.51	35.50	1.33
Surface Gravity (g)	1.00	14.29	2.53
Insolation (S⊕)	1.00	3.84	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	69.800 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 164884002

Gaia DR2

Gaia DR2 2105930840143687680

Gaia DR3

Gaia DR3 2105930840143687680

System

Kepler-55

Percentile among Sub-Neptune cohort

Radius 2.210 R⊕ · percentile 16 / cohort 1978

Mass 69.800 M⊕ · percentile 98 / cohort 1978

Orbital period 42.15 d · percentile 82 / cohort 1946

Distance 578.80 pc · percentile 51 / cohort 1975

ESI 0.464 · percentile 65 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

42.152 days

Semi-major axis

0.2095 AU

Eccentricity

0.000

Inclination

89.96 °

Year Length

A year here lasts approximately 42.15 Earth days (11.5% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2095 AU.

Transit Fingerprint

Depth

0.090 %

Duration

5.062 h

Impact parameter b

0.160

Rp / R★

0.034900

Transit midpoint (BJD)

2,454,971.9928

Photometric dip

Transit produces a flux drop of 896 ppm lasting ≈ 5.06 h.

Extended Orbital Architecture

Planet / star radius ratio

0.034900

Semi-major axis / stellar radius

13.220

Impact parameter (b)

0.160

Transit mid-time (BJD)

2,454,971.9928

Angular separation (arcsec)

0.36200

Eq. Temperature

349K

(76 °C)

Insolation (S⊕)

3.84

Earth = 1.00

Earth Similarity (ESI)

0.464

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — liquid water is physically possible with adequate atmospheric pressure. 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-52 c · Super-Earth Kepler-83 c · Sub-Neptune Kepler-32 d · Sub-Neptune Kepler-83 b · Sub-Neptune Kepler-54 b · Sub-Neptune Kepler-80 c · Sub-Neptune Kepler-81 b · Sub-Neptune

Host System: Kepler-55

Spectral Class

K-type orange

Effective Temperature

4,362 K — cooler than the Sun (5,778 K)

Estimated Age

2.34 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.580 R☉

Stellar Mass

0.620 M☉

Metallicity [Fe/H]

-0.01

Extended Stellar Properties

Surface gravity (log g)

4.700 dex

Stellar density

0.025 g/cm³

Metallicity ratio

[Fe/H]

Distance

578.80 parsec

Light-years 1,887.78 ly

V-band magnitude

15.75 mag

Voyager-speed travel 33,290,961 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

1.699 mas

Total Proper Motion

1.815 mas/yr

PM Right Ascension

-1.78 mas/yr

PM Declination

-0.36 mas/yr

Galactic Cartesian (pc)

x = 0.188 · y = -0.694 · z = 0.695

Equatorial (J2000)

RA 285.16833° · Dec 44.02649°

Galactic ℓ, b

74.258° · 16.925°

Ecliptic λ, β

297.571° · 66.020°

HTM-20 index

84294904

Similar Worlds

Kepler-1026 b

Sub-Neptune · K-type orange

Radius 2.21 R⊕ · 1,145.6 ly

K2-275 c

Sub-Neptune · K-type orange

Radius 2.21 R⊕ · 402.6 ly

Kepler-989 b

Sub-Neptune · K-type orange

Radius 2.21 R⊕ · 1,604.6 ly

Kepler-1874 b

Sub-Neptune · K-type orange

Radius 2.21 R⊕ · 1,330.7 ly

Kepler-169 e

Sub-Neptune · K-type orange

Radius 2.20 R⊕ · 1,325.9 ly

Kepler-229 b

Sub-Neptune · K-type orange

Radius 2.20 R⊕ · 2,694.9 ly

Explore Related Categories

Sub-Neptune Planets Transit Discoveries Kepler Mission K-type orange Hosts