Key parameters at a glance

A radius of 2.67 Earth radii
A mass of 7.61 Earth masses
Surface gravity around 1.07 g
An orbital period of 3.706 days
Semi-major axis 0.0469 AU
Equilibrium temperature 1,281 K (1008 °C)
Distance from Earth 6,839.88 light-years
Earth Similarity Index 0.185
Travel time at Voyager 1 speed 120,621,325 years

Kepler-557 b Planet Profile

Physical Specs

Radius

2.67 R⊕

Radius (Jupiter)

0.238 R♃

Mass

7.61 M⊕

Mass (Jupiter)

0.024 M♃

Density

2.20 g/cm³

Surface Gravity

1.07 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.185

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

#904of 1978

top 45.7%

This planet

2.67R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-357 c 2.67 R⊕ Kepler-96 b 2.67 R⊕ K2-26 b 2.67 R⊕

Metric	Earth	Kepler-557 b	Jupiter
Radius (R⊕)	1.00	2.67	11.21
Mass (M⊕)	1.00	7.61	317.83
Density (g/cm³)	5.51	2.20	1.33
Surface Gravity (g)	1.00	1.07	2.53
Insolation (S⊕)	1.00	2,885.66	0.037

Star Catalogue Identifiers

TIC

TIC 138222081

Gaia DR2

Gaia DR2 2077604981074933120

Gaia DR3

Gaia DR3 2077604981077075712

System

Kepler-557

Percentile among Sub-Neptune cohort

Radius 2.670 R⊕ · percentile 53 / cohort 1978

Mass 7.610 M⊕ · percentile 49 / cohort 1978

Orbital period 3.71 d · percentile 7 / cohort 1946

Distance 2,097.12 pc · percentile 98 / cohort 1975

ESI 0.185 · percentile 5 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

3.706 days

Semi-major axis

0.0469 AU

Eccentricity

0.000

Inclination

82.05 °

Year Length

A year here lasts approximately 3.71 Earth days (1.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0469 AU.

Transit Fingerprint

Depth

0.050 %

Duration

5.104 h

Impact parameter b

0.601

Rp / R★

0.021248

Transit midpoint (BJD)

2,455,002.9434

Photometric dip

Transit produces a flux drop of 501 ppm lasting ≈ 5.10 h.

Extended Orbital Architecture

Planet / star radius ratio

0.021248

Semi-major axis / stellar radius

4.600

Impact parameter (b)

0.601

Transit mid-time (BJD)

2,455,002.9434

Angular separation (arcsec)

0.02240

Eq. Temperature

1,281K

(1008 °C)

Insolation (S⊕)

2,885.66

Earth = 1.00

Earth Similarity (ESI)

0.185

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.

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-557

Spectral Class

F-type yellow-white

Effective Temperature

6,068 K — hotter than the Sun (5,778 K)

Estimated Age

3.24 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.160 R☉

Stellar Mass

1.110 M☉

Metallicity [Fe/H]

0.02

Extended Stellar Properties

Surface gravity (log g)

4.350 dex

Stellar density

0.196 g/cm³

Metallicity ratio

[Fe/H]

Distance

2,097.12 parsec

Light-years 6,839.88 ly

V-band magnitude

14.72 mag

Voyager-speed travel 120,621,325 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.449 mas

Total Proper Motion

9.548 mas/yr

PM Right Ascension

-2.21 mas/yr

PM Declination

-9.29 mas/yr

Galactic Cartesian (pc)

x = 0.301 · y = -0.685 · z = 0.664

Equatorial (J2000)

RA 293.70842° · Dec 41.61511°

Galactic ℓ, b

74.676° · 10.230°

Ecliptic λ, β

309.558° · 61.837°

HTM-20 index

-931797312