Key parameters at a glance

A radius of 0.50 Earth radii
A mass of 0.08 Earth masses
Surface gravity around 0.32 g
An orbital period of 4.546 days
Semi-major axis 0.0488 AU
Equilibrium temperature 868 K (595 °C)
Distance from Earth 118.85 light-years
Earth Similarity Index 0.303
Travel time at Voyager 1 speed 2,095,919 years
Almost certainly tidally locked to its host star given the close orbit

4 siblings around Kepler-444

Kepler-444 c shares its host star with 4 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-444 b	Rocky Terrestrial	0.40	0.04	3.600	938	2015
Kepler-444 c this	Rocky Terrestrial	0.50	0.08	4.546	868	2015
Kepler-444 d	Rocky Terrestrial	0.53	0.20	6.189	783	2015
Kepler-444 e	Rocky Terrestrial	0.55	0.10	7.743	727	2015
Kepler-444 f	Rocky Terrestrial	0.74	0.33	9.740	673	2015

Kepler-444 c Planet Profile

Physical Specs

Radius

0.50 R⊕

Radius (Jupiter)

0.044 R♃

Mass

0.08 M⊕

Mass (Jupiter)

0.000 M♃

Density

3.55 g/cm³

Surface Gravity

0.32 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.303

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

#563of 570

top 98.6%

This planet

0.50R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-1489 c 0.51 R⊕ Kepler-1994 b 0.51 R⊕ KOI-4777.01 0.51 R⊕

Metric	Earth	Kepler-444 c	Jupiter
Radius (R⊕)	1.00	0.50	11.21
Mass (M⊕)	1.00	0.08	317.83
Density (g/cm³)	5.51	3.55	1.33
Surface Gravity (g)	1.00	0.32	2.53
Insolation (S⊕)	1.00	165.73	0.037

Star Catalogue Identifiers

HIP

HIP 94931

TIC

TIC 394172596

Gaia DR2

Gaia DR2 2101486923385239808

Gaia DR3

Gaia DR3 2101486923385239808

System

Kepler-444

Percentile among Rocky Terrestrial cohort

Radius 0.497 R⊕ · percentile 1 / cohort 570

Mass 0.079 M⊕ · percentile 1 / cohort 570

Orbital period 4.55 d · percentile 50 / cohort 567

Distance 36.44 pc · percentile 15 / cohort 566

ESI 0.303 · percentile 39 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

4.546 days

Semi-major axis

0.0488 AU

Eccentricity

0.310

Inclination

88.20 °

Year Length

A year here lasts approximately 4.55 Earth days (1.2% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.0488 AU.

Transit Fingerprint

Depth

0.004 %

Duration

1.737 h

Impact parameter b

0.420

Rp / R★

0.006050

Transit midpoint (BJD)

2,454,964.5220

Photometric dip

Transit produces a flux drop of 44 ppm lasting ≈ 1.74 h.

Extended Orbital Architecture

Planet / star radius ratio

0.006050

Semi-major axis / stellar radius

13.961

Impact parameter (b)

0.420

Transit mid-time (BJD)

2,454,964.5220

Angular separation (arcsec)

1.34000

Eq. Temperature

868K

(595 °C)

Insolation (S⊕)

165.73

Earth = 1.00

Earth Similarity (ESI)

0.303

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.

Discovery Paper

Primary reference

Campante et al. 2015

Instrument

Kepler CCD Array

Publication

2015-02

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-444

Spectral Class

K-type orange

Effective Temperature

5,046 K — cooler than the Sun (5,778 K)

Estimated Age

11.23 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.752 R☉

Stellar Mass

0.758 M☉

Metallicity [Fe/H]

-0.55

Extended Stellar Properties

Surface gravity (log g)

4.563 dex

Stellar density

2.493 g/cm³

Systemic radial velocity

-121.90 km/s

Rotational v·sin i

2.00 km/s

Metallicity ratio

[Fe/H]

Distance

36.44 parsec

Light-years 118.85 ly

V-band magnitude

8.87 mag

Voyager-speed travel 2,095,919 yr

Multi-band Host Photometry — 15 bands

Astrometric Data

Parallax

27.414 mas

Total Proper Motion

639.253 mas/yr

PM Right Ascension

94.68 mas/yr

PM Declination

-632.20 mas/yr

Galactic Cartesian (pc)

x = 0.253 · y = -0.703 · z = 0.664

Equatorial (J2000)

RA 289.75283° · Dec 41.63188°

Galactic ℓ, b

73.361° · 12.891°

Ecliptic λ, β

303.531° · 62.790°

HTM-20 index

-1506167882