Key parameters at a glance

A radius of 2.38 Earth radii
A mass of 6.26 Earth masses
Surface gravity around 1.11 g
An orbital period of 10.214 days
Semi-major axis 0.0936 AU
Equilibrium temperature 957 K (684 °C)
Distance from Earth 2,773.12 light-years
Earth Similarity Index 0.267
Travel time at Voyager 1 speed 48,903,886 years

Kepler-639 b Planet Profile

Physical Specs

Radius

2.38 R⊕

Radius (Jupiter)

0.212 R♃

Mass

6.26 M⊕

Mass (Jupiter)

0.020 M♃

Density

2.55 g/cm³

Surface Gravity

1.11 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.267

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

#1365of 1978

top 69.0%

This planet

2.38R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-166 c 2.38 R⊕ Kepler-189 c 2.38 R⊕ Kepler-1249 b 2.38 R⊕

Metric	Earth	Kepler-639 b	Jupiter
Radius (R⊕)	1.00	2.38	11.21
Mass (M⊕)	1.00	6.26	317.83
Density (g/cm³)	5.51	2.55	1.33
Surface Gravity (g)	1.00	1.11	2.53
Insolation (S⊕)	1.00	295.83	0.037

Star Catalogue Identifiers

TIC

TIC 137409501

Gaia DR2

Gaia DR2 2101675661427506432

Gaia DR3

Gaia DR3 2101675661427506432

System

Kepler-639

Percentile among Sub-Neptune cohort

Radius 2.380 R⊕ · percentile 31 / cohort 1978

Mass 6.260 M⊕ · percentile 29 / cohort 1978

Orbital period 10.21 d · percentile 35 / cohort 1946

Distance 850.24 pc · percentile 69 / cohort 1975

ESI 0.267 · percentile 20 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

10.214 days

Semi-major axis

0.0936 AU

Eccentricity

0.000

Inclination

89.93 °

Year Length

A year here lasts approximately 10.21 Earth days (2.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0936 AU.

Transit Fingerprint

Depth

0.030 %

Duration

5.856 h

Impact parameter b

0.886

Rp / R★

0.016734

Transit midpoint (BJD)

2,455,003.7036

Photometric dip

Transit produces a flux drop of 304 ppm lasting ≈ 5.86 h.

Extended Orbital Architecture

Planet / star radius ratio

0.016734

Semi-major axis / stellar radius

13.630

Impact parameter (b)

0.886

Transit mid-time (BJD)

2,455,003.7036

Angular separation (arcsec)

0.11000

Eq. Temperature

957K

(684 °C)

Insolation (S⊕)

295.83

Earth = 1.00

Earth Similarity (ESI)

0.267

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-639

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,896 K — hotter than the Sun (5,778 K)

Estimated Age

4.37 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.290 R☉

Stellar Mass

1.140 M☉

Metallicity [Fe/H]

0.23

Extended Stellar Properties

Surface gravity (log g)

4.270 dex

Stellar density

0.260 g/cm³

Metallicity ratio

[Fe/H]

Distance

850.24 parsec

Light-years 2,773.12 ly

V-band magnitude

13.36 mag

Voyager-speed travel 48,903,886 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

1.147 mas

Total Proper Motion

23.389 mas/yr

PM Right Ascension

-5.15 mas/yr

PM Declination

-22.81 mas/yr

Galactic Cartesian (pc)

x = 0.282 · y = -0.691 · z = 0.666

Equatorial (J2000)

RA 292.18683° · Dec 41.72694°

Galactic ℓ, b

74.255° · 11.294°

Ecliptic λ, β

307.346° · 62.319°

HTM-20 index

-327058931