Key parameters at a glance

A radius of 1.27 Earth radii
A mass of 2.15 Earth masses
Surface gravity around 1.33 g
An orbital period of 22.408 days
Semi-major axis 0.1100 AU
Equilibrium temperature 319 K (46 °C)
Distance from Earth 579.23 light-years
Earth Similarity Index 0.885
Travel time at Voyager 1 speed 10,214,782 years
Almost certainly tidally locked to its host star given the close orbit

Context from the literature

Kepler-186e is a confirmed exoplanet orbiting the red dwarf star Kepler-186, approximately 582 light years away from Earth in the constellation of Cygnus. It is near the optimistic habitable zone but probably not in it, possibly making it have a runaway greenhouse effect, like Venus. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. Four additional planets orbiting the star were also discovered.

Excerpted from Wikipedia · full article

3 siblings around Kepler-186

Kepler-186 e 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-186 b	Rocky Terrestrial	1.07	1.24	3.887	571	2014
Kepler-186 c	Super-Earth	1.25	2.10	7.267	464	2014
Kepler-186 d	Super-Earth	1.40	2.54	13.343	379	2014
Kepler-186 e this	Super-Earth	1.27	2.15	22.408	319	2014

Kepler-186 e Planet Profile

Physical Specs

Radius

1.27 R⊕

Radius (Jupiter)

0.113 R♃

Mass

2.15 M⊕

Mass (Jupiter)

0.007 M♃

Density

5.77 g/cm³

Surface Gravity

1.33 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.885

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

#1135of 1176

top 96.4%

This planet

1.27R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-85 e 1.27 R⊕ Kepler-404 b 1.27 R⊕ Kepler-181 b 1.27 R⊕

Metric	Earth	Kepler-186 e	Jupiter
Radius (R⊕)	1.00	1.27	11.21
Mass (M⊕)	1.00	2.15	317.83
Density (g/cm³)	5.51	5.77	1.33
Surface Gravity (g)	1.00	1.33	2.53
Insolation (S⊕)	1.00	3.61	0.037

Star Catalogue Identifiers

TIC

TIC 268159861

Gaia DR2

Gaia DR2 2079000330051813504

Gaia DR3

Gaia DR3 2079000330051813504

System

Kepler-186

Percentile among Super-Earth cohort

Radius 1.270 R⊕ · percentile 3 / cohort 1176

Mass 2.150 M⊕ · percentile 4 / cohort 1176

Orbital period 22.41 d · percentile 87 / cohort 1164

Distance 177.59 pc · percentile 22 / cohort 1171

ESI 0.885 · percentile 96 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

22.408 days

Semi-major axis

0.1100 AU

Eccentricity

0.000

Inclination

89.84 °

Year Length

A year here lasts approximately 22.41 Earth days (6.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1100 AU.

Transit Fingerprint

Depth

0.071 %

Duration

3.320 h

Impact parameter b

0.310

Rp / R★

0.024650

Transit midpoint (BJD)

2,454,986.8006

Photometric dip

Transit produces a flux drop of 709 ppm lasting ≈ 3.32 h.

Extended Orbital Architecture

Planet / star radius ratio

0.024650

Semi-major axis / stellar radius

52.750

Impact parameter (b)

0.310

Transit mid-time (BJD)

2,454,986.8006

Angular separation (arcsec)

0.61900

Eq. Temperature

319K

(46 °C)

Insolation (S⊕)

3.61

Earth = 1.00

Earth Similarity (ESI)

0.885

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — liquid water is physically possible with adequate atmospheric pressure. Close-orbiting tidally-locked around a cool host.

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-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 Kepler-220 d · Rocky Terrestrial

Host System: Kepler-186

Spectral Class

M-type red dwarf

Effective Temperature

3,788 K — cooler than the Sun (5,778 K)

Estimated Age

4.00 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.472 R☉

Stellar Mass

0.478 M☉

Metallicity [Fe/H]

-0.28

Extended Stellar Properties

Surface gravity (log g)

4.770 dex

Stellar density

6.400 g/cm³

Metallicity ratio

[M/H]

Distance

177.59 parsec

Light-years 579.23 ly

V-band magnitude

15.14 mag

Voyager-speed travel 10,214,782 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

5.602 mas

Total Proper Motion

4.839 mas/yr

PM Right Ascension

2.10 mas/yr

PM Declination

-4.36 mas/yr

Galactic Cartesian (pc)

x = 0.345 · y = -0.632 · z = 0.694

Equatorial (J2000)

RA 298.65274° · Dec 43.95499°

Galactic ℓ, b

78.520° · 8.171°

Ecliptic λ, β

318.672° · 62.636°

HTM-20 index

1990400524

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