Key parameters at a glance

A radius of 8.65 Earth radii
A mass of 56.00 Earth masses
Surface gravity around 0.75 g
An orbital period of 49.184 days
Semi-major axis 0.2920 AU
Equilibrium temperature 669 K (396 °C)
Distance from Earth 1,104.79 light-years
Earth Similarity Index 0.218
Travel time at Voyager 1 speed 19,483,054 years

1 sibling around Kepler-108

Kepler-108 b shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-108 b this	Neptune-like	8.65	56.00	49.184	669	2014
Kepler-108 c	Neptune-like	8.18	50.90	190.323	426	2014

Kepler-108 b Planet Profile

Physical Specs

Radius

8.65 R⊕

Radius (Jupiter)

0.772 R♃

Mass

56.00 M⊕

Mass (Jupiter)

0.176 M♃

Density

0.48 g/cm³

Surface Gravity

0.75 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.218

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

#110of 574

top 19.0%

This planet

8.65R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

WASP-29 b 8.63 R⊕ TOI-2525 b 8.68 R⊕ K2-329 b 8.68 R⊕

Metric	Earth	Kepler-108 b	Jupiter
Radius (R⊕)	1.00	8.65	11.21
Mass (M⊕)	1.00	56.00	317.83
Density (g/cm³)	5.51	0.48	1.33
Surface Gravity (g)	1.00	0.75	2.53
Insolation (S⊕)	1.00	47.40	0.037

Star Catalogue Identifiers

TIC

TIC 271164755

Gaia DR2

Gaia DR2 2080062630075994624

System

Kepler-108

Percentile among Neptune-like cohort

Radius 8.650 R⊕ · percentile 81 / cohort 574

Mass 56.000 M⊕ · percentile 76 / cohort 574

Orbital period 49.18 d · percentile 70 / cohort 524

Distance 338.73 pc · percentile 50 / cohort 572

ESI 0.218 · percentile 31 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

49.184 days

Semi-major axis

0.2920 AU

Eccentricity

0.220

Inclination

89.94 °

Year Length

A year here lasts approximately 49.18 Earth days (13.5% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.2920 AU.

Transit Fingerprint

Depth

0.165 %

Duration

11.277 h

Impact parameter b

0.030

Rp / R★

0.037540

Transit midpoint (BJD)

2,454,974.9112

Photometric dip

Transit produces a flux drop of 1,646 ppm lasting ≈ 11.28 h.

Extended Orbital Architecture

Planet / star radius ratio

0.037540

Semi-major axis / stellar radius

28.730

Impact parameter (b)

0.030

Transit mid-time (BJD)

2,454,974.9112

Angular separation (arcsec)

0.86200

Eq. Temperature

669K

(396 °C)

Insolation (S⊕)

47.40

Earth = 1.00

Earth Similarity (ESI)

0.218

0 = alien, 1 = Earth-identical

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

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

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-108

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,854 K — hotter than the Sun (5,778 K)

Estimated Age

3.89 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

2.192 R☉

Stellar Mass

1.247 M☉

Metallicity [Fe/H]

0.33

Extended Stellar Properties

Surface gravity (log g)

3.895 dex

Stellar density

0.243 g/cm³

Metallicity ratio

[M/H]

Distance

338.73 parsec

Light-years 1,104.79 ly

V-band magnitude

12.66 mag

Voyager-speed travel 19,483,054 yr