Key parameters at a glance

A radius of 2.63 Earth radii
A mass of 7.41 Earth masses
Surface gravity around 1.07 g
An orbital period of 40.607 days
Semi-major axis 0.2259 AU
Equilibrium temperature 521 K (248 °C)
Distance from Earth 2,295.35 light-years
Earth Similarity Index 0.469
Travel time at Voyager 1 speed 40,478,476 years

Kepler-581 b Planet Profile

Physical Specs

Radius

2.63 R⊕

Radius (Jupiter)

0.235 R♃

Mass

7.41 M⊕

Mass (Jupiter)

0.023 M♃

Density

2.24 g/cm³

Surface Gravity

1.07 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.469

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

#969of 1978

top 48.9%

This planet

2.63R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-1241 b 2.63 R⊕ GJ 3473 c 2.63 R⊕ Kepler-319 c 2.63 R⊕

Metric	Earth	Kepler-581 b	Jupiter
Radius (R⊕)	1.00	2.63	11.21
Mass (M⊕)	1.00	7.41	317.83
Density (g/cm³)	5.51	2.24	1.33
Surface Gravity (g)	1.00	1.07	2.53
Insolation (S⊕)	1.00	12.39	0.037

Star Catalogue Identifiers

TIC

TIC 184009313

Gaia DR2

Gaia DR2 2076595869920511104

Gaia DR3

Gaia DR3 2076595869920511104

System

Kepler-581

Percentile among Sub-Neptune cohort

Radius 2.630 R⊕ · percentile 50 / cohort 1978

Mass 7.410 M⊕ · percentile 46 / cohort 1978

Orbital period 40.61 d · percentile 81 / cohort 1946

Distance 703.76 pc · percentile 60 / cohort 1975

ESI 0.469 · percentile 66 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

40.607 days

Semi-major axis

0.2259 AU

Eccentricity

0.000

Inclination

89.41 °

Year Length

A year here lasts approximately 40.61 Earth days (11.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2259 AU.

Transit Fingerprint

Depth

0.070 %

Duration

5.719 h

Impact parameter b

0.028

Rp / R★

0.023877

Transit midpoint (BJD)

2,455,032.2578

Photometric dip

Transit produces a flux drop of 696 ppm lasting ≈ 5.72 h.

Extended Orbital Architecture

Planet / star radius ratio

0.023877

Semi-major axis / stellar radius

55.520

Impact parameter (b)

0.028

Transit mid-time (BJD)

2,455,032.2578

Angular separation (arcsec)

0.32100

Eq. Temperature

521K

(248 °C)

Insolation (S⊕)

12.39

Earth = 1.00

Earth Similarity (ESI)

0.469

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-581

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,772 K — cooler than the Sun (5,778 K)

Estimated Age

4.07 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.000 R☉

Stellar Mass

1.000 M☉

Metallicity [Fe/H]

0.03

Extended Stellar Properties

Surface gravity (log g)

4.440 dex

Stellar density

1.963 g/cm³

Metallicity ratio

[Fe/H]

Distance

703.76 parsec

Light-years 2,295.35 ly

V-band magnitude

14.70 mag

Voyager-speed travel 40,478,476 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

1.393 mas

Total Proper Motion

24.958 mas/yr

PM Right Ascension

-21.36 mas/yr

PM Declination

-12.92 mas/yr

Galactic Cartesian (pc)

x = 0.326 · y = -0.685 · z = 0.651

Equatorial (J2000)

RA 295.43266° · Dec 40.64819°

Galactic ℓ, b

74.427° · 8.629°

Ecliptic λ, β

311.400° · 60.484°

HTM-20 index

-1497048047