Key parameters at a glance

A radius of 2.43 Earth radii
A mass of 43.00 Earth masses
Surface gravity around 7.28 g
An orbital period of 27.948 days
Semi-major axis 0.1593 AU
Equilibrium temperature 400 K (127 °C)
Distance from Earth 1,887.78 light-years
Earth Similarity Index 0.508
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 b 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 this	Sub-Neptune	2.43	43.00	27.948	400	2012
Kepler-55 c	Sub-Neptune	2.21	69.80	42.152	349	2012

Kepler-55 b Planet Profile

Physical Specs

Radius

2.43 R⊕

Radius (Jupiter)

0.217 R♃

Mass

43.00 M⊕

Mass (Jupiter)

0.135 M♃

Density

16.50 g/cm³

Surface Gravity

7.28 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.508

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

#1281of 1978

top 64.7%

This planet

2.43R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

TOI-4184 b 2.43 R⊕ Kepler-233 b 2.43 R⊕ GJ 887 c 2.43 R⊕

Metric	Earth	Kepler-55 b	Jupiter
Radius (R⊕)	1.00	2.43	11.21
Mass (M⊕)	1.00	43.00	317.83
Density (g/cm³)	5.51	16.50	1.33
Surface Gravity (g)	1.00	7.28	2.53
Insolation (S⊕)	1.00	6.64	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	43.000 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 2.430 R⊕ · percentile 35 / cohort 1978

Mass 43.000 M⊕ · percentile 97 / cohort 1978

Orbital period 27.95 d · percentile 72 / cohort 1946

Distance 578.80 pc · percentile 51 / cohort 1975

ESI 0.508 · percentile 71 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

27.948 days

Semi-major axis

0.1593 AU

Eccentricity

0.000

Inclination

89.94 °

Year Length

A year here lasts approximately 27.95 Earth days (7.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1593 AU.

Transit Fingerprint

Depth

0.094 %

Duration

3.493 h

Impact parameter b

0.063

Rp / R★

0.038320

Transit midpoint (BJD)

2,455,011.7960

Photometric dip

Transit produces a flux drop of 943 ppm lasting ≈ 3.49 h.

Extended Orbital Architecture

Planet / star radius ratio

0.038320

Semi-major axis / stellar radius

12.460

Impact parameter (b)

0.063

Transit mid-time (BJD)

2,455,011.7960

Angular separation (arcsec)

0.27500

Eq. Temperature

400K

(127 °C)

Insolation (S⊕)

6.64

Earth = 1.00

Earth Similarity (ESI)

0.508

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-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-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-1526 b

Sub-Neptune · K-type orange

Radius 2.43 R⊕ · 1,812.0 ly

K2-324 b

Sub-Neptune · K-type orange

Radius 2.43 R⊕ · 445.7 ly

Kepler-786 b

Sub-Neptune · K-type orange

Radius 2.43 R⊕ · 1,582.9 ly

TOI-904 b

Sub-Neptune · K-type orange

Radius 2.43 R⊕ · 150.3 ly

Kepler-1716 b

Sub-Neptune · K-type orange

Radius 2.42 R⊕ · 637.4 ly

Kepler-1858 b

Sub-Neptune · K-type orange

Radius 2.42 R⊕ · 2,717.1 ly

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