Key parameters at a glance

A radius of 2.78 Earth radii
A mass of 5.12 Earth masses
Surface gravity around 0.66 g
An orbital period of 12.280 days
Semi-major axis 0.0855 AU
Equilibrium temperature 431 K (158 °C)
Distance from Earth 1,093.62 light-years
Earth Similarity Index 0.500
Travel time at Voyager 1 speed 19,286,056 years
Almost certainly tidally locked to its host star given the close orbit

3 siblings around Kepler-26

Kepler-26 b shares its host star with 3 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-26 d	Rocky Terrestrial	1.07	1.24	3.544	652	2014
Kepler-26 b this	Sub-Neptune	2.78	5.12	12.280	431	2011
Kepler-26 c	Sub-Neptune	2.72	6.20	17.256	385	2011
Kepler-26 e	Sub-Neptune	2.41	6.39	46.828	276	2014

Kepler-26 b Planet Profile

Physical Specs

Radius

2.78 R⊕

Radius (Jupiter)

0.248 R♃

Mass

5.12 M⊕

Mass (Jupiter)

0.016 M♃

Density

1.26 g/cm³

Surface Gravity

0.66 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.500

HZ Position Inner

Controversial No

Discovery

Year 2011

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#768of 1978

top 38.8%

This planet

2.78R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-58 b 2.78 R⊕ Kepler-531 b 2.78 R⊕ K2-284 b 2.78 R⊕

Metric	Earth	Kepler-26 b	Jupiter
Radius (R⊕)	1.00	2.78	11.21
Mass (M⊕)	1.00	5.12	317.83
Density (g/cm³)	5.51	1.26	1.33
Surface Gravity (g)	1.00	0.66	2.53
Insolation (S⊕)	1.00	7.60	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	5.120 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 164833065

Gaia DR2

Gaia DR2 2107317358665730688

Gaia DR3

Gaia DR3 2107317358665730688

System

Kepler-26

Percentile among Sub-Neptune cohort

Radius 2.780 R⊕ · percentile 61 / cohort 1978

Mass 5.120 M⊕ · percentile 10 / cohort 1978

Orbital period 12.28 d · percentile 42 / cohort 1946

Distance 335.31 pc · percentile 38 / cohort 1975

ESI 0.500 · percentile 70 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

12.280 days

Semi-major axis

0.0855 AU

Eccentricity

0.021

Inclination

89.93 °

Year Length

A year here lasts approximately 12.28 Earth days (3.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0855 AU.

Transit Fingerprint

Depth

0.279 %

Duration

2.710 h

Impact parameter b

0.475

Rp / R★

0.048233

Transit midpoint (BJD)

2,456,471.2497

Photometric dip

Transit produces a flux drop of 2,795 ppm lasting ≈ 2.71 h.

Extended Orbital Architecture

Planet / star radius ratio

0.048233

Semi-major axis / stellar radius

36.270

Impact parameter (b)

0.475

Transit mid-time (BJD)

2,456,471.2497

Angular separation (arcsec)

0.25500

Eq. Temperature

431K

(158 °C)

Insolation (S⊕)

7.60

Earth = 1.00

Earth Similarity (ESI)

0.500

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. 2012

Instrument

Kepler CCD Array

Publication

2012-04

Observation locale

Space

Discovery cohort

Planets confirmed in 2011 at Kepler (12 shown).

Kepler-22 b · Sub-Neptune Kepler-20 d · Sub-Neptune Kepler-26 c · Sub-Neptune Kepler-19 c · Sub-Neptune Kepler-28 c · Super-Earth Kepler-10 c · Sub-Neptune Kepler-20 f · Rocky Terrestrial Kepler-42 d · Rocky Terrestrial Kepler-16 b · Neptune-like Kepler-28 b · Super-Earth Kepler-34 b · Neptune-like Kepler-29 c · Sub-Neptune

Host System: Kepler-26

Spectral Class

M-type red dwarf

Effective Temperature

3,914 K — cooler than the Sun (5,778 K)

Estimated Age

2.95 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.512 R☉

Stellar Mass

0.544 M☉

Metallicity [Fe/H]

-0.13

Extended Stellar Properties

Surface gravity (log g)

4.680 dex

Stellar density

5.983 g/cm³

Rotational v·sin i

1.90 km/s

Metallicity ratio

[Fe/H]

Distance

335.31 parsec

Light-years 1,093.62 ly

V-band magnitude

15.85 mag

Voyager-speed travel 19,286,056 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

2.954 mas

Total Proper Motion

16.909 mas/yr

PM Right Ascension

9.54 mas/yr

PM Declination

-13.96 mas/yr

Galactic Cartesian (pc)

x = 0.177 · y = -0.664 · z = 0.726

Equatorial (J2000)

RA 284.94106° · Dec 46.56645°

Galactic ℓ, b

76.680° · 17.993°

Ecliptic λ, β

298.934° · 68.510°

HTM-20 index

-1382944939