Key parameters at a glance

A radius of 2.70 Earth radii
A mass of 7.75 Earth masses
Surface gravity around 1.06 g
An orbital period of 8.354 days
Semi-major axis 0.0768 AU
Equilibrium temperature 790 K (517 °C)
Distance from Earth 2,559.08 light-years
Earth Similarity Index 0.311
Travel time at Voyager 1 speed 45,129,350 years

Kepler-668 b Planet Profile

Physical Specs

Radius

2.70 R⊕

Radius (Jupiter)

0.241 R♃

Mass

7.75 M⊕

Mass (Jupiter)

0.024 M♃

Density

2.16 g/cm³

Surface Gravity

1.06 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.311

HZ Position Inner

Controversial No

Discovery

Year 2016

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#865of 1978

top 43.7%

This planet

2.70R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-259 c 2.70 R⊕ Kepler-1452 b 2.70 R⊕ Kepler-32 d 2.70 R⊕

Metric	Earth	Kepler-668 b	Jupiter
Radius (R⊕)	1.00	2.70	11.21
Mass (M⊕)	1.00	7.75	317.83
Density (g/cm³)	5.51	2.16	1.33
Surface Gravity (g)	1.00	1.06	2.53
Insolation (S⊕)	1.00	77.62	0.037

Star Catalogue Identifiers

TIC

TIC 350813835

Gaia DR2

Gaia DR2 2132007888699166848

Gaia DR3

Gaia DR3 2132007888699166848

System

Kepler-668

Percentile among Sub-Neptune cohort

Radius 2.700 R⊕ · percentile 56 / cohort 1978

Mass 7.750 M⊕ · percentile 51 / cohort 1978

Orbital period 8.35 d · percentile 27 / cohort 1946

Distance 784.62 pc · percentile 65 / cohort 1975

ESI 0.311 · percentile 31 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

8.354 days

Semi-major axis

0.0768 AU

Eccentricity

0.000

Inclination

89.95 °

Year Length

A year here lasts approximately 8.35 Earth days (2.3% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0768 AU.

Transit Fingerprint

Depth

0.104 %

Duration

2.271 h

Impact parameter b

0.023

Rp / R★

0.029736

Transit midpoint (BJD)

2,455,004.6326

Photometric dip

Transit produces a flux drop of 1,042 ppm lasting ≈ 2.27 h.

Extended Orbital Architecture

Planet / star radius ratio

0.029736

Semi-major axis / stellar radius

29.180

Impact parameter (b)

0.023

Transit mid-time (BJD)

2,455,004.6326

Angular separation (arcsec)

0.09790

Eq. Temperature

790K

(517 °C)

Insolation (S⊕)

77.62

Earth = 1.00

Earth Similarity (ESI)

0.311

0 = alien, 1 = Earth-identical

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

Discovery Paper

Primary reference

Morton et al. 2016

Instrument

Kepler CCD Array

Publication

2016-05

Observation locale

Space

Discovery cohort

Planets confirmed in 2016 at Kepler (12 shown).

Kepler-1512 b · Rocky Terrestrial Kepler-1410 b · Super-Earth Kepler-560 b · Super-Earth Kepler-1389 b · Super-Earth Kepler-1450 b · Super-Earth Kepler-1544 b · Super-Earth Kepler-1459 b · Super-Earth Kepler-1638 b · Super-Earth Kepler-737 b · Super-Earth Kepler-1185 b · Super-Earth Kepler-1178 b · Rocky Terrestrial Kepler-1040 b · Sub-Neptune

Host System: Kepler-668

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,352 K — cooler than the Sun (5,778 K)

Estimated Age

3.89 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.820 R☉

Stellar Mass

0.870 M☉

Metallicity [Fe/H]

-0.06

Extended Stellar Properties

Surface gravity (log g)

4.550 dex

Stellar density

6.732 g/cm³

Metallicity ratio

[Fe/H]

Distance

784.62 parsec

Light-years 2,559.08 ly

V-band magnitude

15.37 mag

Voyager-speed travel 45,129,350 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

1.246 mas

Total Proper Motion

13.136 mas/yr

PM Right Ascension

1.10 mas/yr

PM Declination

-13.09 mas/yr

Galactic Cartesian (pc)

x = 0.174 · y = -0.629 · z = 0.758

Equatorial (J2000)

RA 285.49928° · Dec 49.27727°

Galactic ℓ, b

79.492° · 18.593°

Ecliptic λ, β

302.338° · 70.981°

HTM-20 index

-356611003