Key parameters at a glance

A radius of 1.11 Earth radii
A mass of 1.41 Earth masses
Surface gravity around 1.14 g
An orbital period of 3.036 days
Semi-major axis 0.0283 AU
Equilibrium temperature 520 K (247 °C)
Distance from Earth 314.22 light-years
Earth Similarity Index 0.610
Travel time at Voyager 1 speed 5,541,189 years
Almost certainly tidally locked to its host star given the close orbit

2 siblings around Kepler-446

Kepler-446 c shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-446 b	Super-Earth	1.50	2.86	1.565	648	2015
Kepler-446 c this	Rocky Terrestrial	1.11	1.41	3.036	520	2015
Kepler-446 d	Super-Earth	1.35	2.39	5.149	436	2015

Kepler-446 c Planet Profile

Physical Specs

Radius

1.11 R⊕

Radius (Jupiter)

0.100 R♃

Mass

1.41 M⊕

Mass (Jupiter)

0.004 M♃

Density

5.67 g/cm³

Surface Gravity

1.14 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.610

HZ Position Inner

Controversial No

Discovery

Year 2015

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#209of 570

top 36.5%

This planet

1.11R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-124 d 1.11 R⊕ Kepler-327 b 1.11 R⊕ Kepler-333 c 1.11 R⊕

Metric	Earth	Kepler-446 c	Jupiter
Radius (R⊕)	1.00	1.11	11.21
Mass (M⊕)	1.00	1.41	317.83
Density (g/cm³)	5.51	5.67	1.33
Surface Gravity (g)	1.00	1.14	2.53
Insolation (S⊕)	1.00	6.71	0.037

Star Catalogue Identifiers

TIC

TIC 123417850

Gaia DR2

Gaia DR2 2106929849536047744

Gaia DR3

Gaia DR3 2106929849536047744

System

Kepler-446

Percentile among Rocky Terrestrial cohort

Radius 1.110 R⊕ · percentile 61 / cohort 570

Mass 1.410 M⊕ · percentile 56 / cohort 570

Orbital period 3.04 d · percentile 34 / cohort 567

Distance 96.34 pc · percentile 23 / cohort 566

ESI 0.610 · percentile 79 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

3.036 days

Semi-major axis

0.0283 AU

Eccentricity

0.000

Inclination

88.97 °

Year Length

A year here lasts approximately 3.04 Earth days (0.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0283 AU.

Transit Fingerprint

Depth

0.182 %

Duration

0.943 h

Impact parameter b

0.025

Rp / R★

0.042400

Transit midpoint (BJD)

2,454,967.0696

Photometric dip

Transit produces a flux drop of 1,821 ppm lasting ≈ 0.94 h.

Extended Orbital Architecture

Planet / star radius ratio

0.042400

Semi-major axis / stellar radius

22.400

Impact parameter (b)

0.025

RV semi-amplitude (K)

3.500 m/s

Transit mid-time (BJD)

2,454,967.0696

Angular separation (arcsec)

0.29400

Eq. Temperature

520K

(247 °C)

Insolation (S⊕)

6.71

Earth = 1.00

Earth Similarity (ESI)

0.610

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.

Radial velocity

Stellar wobble has been measured spectroscopically.

Discovery Paper

Primary reference

Muirhead et al. 2015

Instrument

Kepler CCD Array

Publication

2015-03

Observation locale

Space

Discovery cohort

Planets confirmed in 2015 at Kepler (12 shown).

Kepler-438 b · Rocky Terrestrial Kepler-445 d · Super-Earth Kepler-442 b · Super-Earth Kepler-439 b · Sub-Neptune Kepler-437 b · Sub-Neptune Kepler-440 b · Super-Earth KIC 8540376 c · Sub-Neptune Kepler-445 b · Super-Earth Kepler-446 d · Super-Earth Kepler-436 b · Sub-Neptune Kepler-445 c · Sub-Neptune Kepler-443 b · Sub-Neptune

Host System: Kepler-446

Spectral Class

M-type red dwarf

Effective Temperature

3,359 K — cooler than the Sun (5,778 K)

Estimated Age

3.72 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.240 R☉

Stellar Mass

0.220 M☉

Metallicity [Fe/H]

-0.30

Extended Stellar Properties

Surface gravity (log g)

5.033 dex

Stellar density

25.357 g/cm³

Systemic radial velocity

-118.00 km/s

Metallicity ratio

[Fe/H]

Distance

96.34 parsec

Light-years 314.22 ly

V-band magnitude

17.50 mag

Voyager-speed travel 5,541,189 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

10.352 mas

Total Proper Motion

27.054 mas/yr

PM Right Ascension

-12.47 mas/yr

PM Declination

-24.01 mas/yr

Galactic Cartesian (pc)

x = 0.150 · y = -0.692 · z = 0.706

Equatorial (J2000)

RA 282.25010° · Dec 44.92100°

Galactic ℓ, b

74.368° · 19.189°

Ecliptic λ, β

292.994° · 67.385°

HTM-20 index

-366222039