Key parameters at a glance

A radius of 3.18 Earth radii
A mass of 10.20 Earth masses
Surface gravity around 1.01 g
An orbital period of 22.208 days
Semi-major axis 0.1712 AU
Equilibrium temperature 803 K (530 °C)
Distance from Earth 2,709.18 light-years
Earth Similarity Index 0.286
Travel time at Voyager 1 speed 47,776,310 years

Kepler-521 b Planet Profile

Physical Specs

Radius

3.18 R⊕

Radius (Jupiter)

0.284 R♃

Mass

10.20 M⊕

Mass (Jupiter)

0.032 M♃

Density

1.74 g/cm³

Surface Gravity

1.01 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.286

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

#367of 1978

top 18.5%

This planet

3.18R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

TOI-2458 c 3.18 R⊕ Kepler-1502 b 3.18 R⊕ NGTS-4 b 3.18 R⊕

Metric	Earth	Kepler-521 b	Jupiter
Radius (R⊕)	1.00	3.18	11.21
Mass (M⊕)	1.00	10.20	317.83
Density (g/cm³)	5.51	1.74	1.33
Surface Gravity (g)	1.00	1.01	2.53
Insolation (S⊕)	1.00	160.61	0.037

Star Catalogue Identifiers

TIC

TIC 268302011

Gaia DR2

Gaia DR2 2079005651508492032

Gaia DR3

Gaia DR3 2079005651508492032

System

Kepler-521

Percentile among Sub-Neptune cohort

Radius 3.180 R⊕ · percentile 81 / cohort 1978

Mass 10.200 M⊕ · percentile 74 / cohort 1978

Orbital period 22.21 d · percentile 66 / cohort 1946

Distance 830.64 pc · percentile 67 / cohort 1975

ESI 0.286 · percentile 25 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

22.208 days

Semi-major axis

0.1712 AU

Eccentricity

0.000

Inclination

89.96 °

Year Length

A year here lasts approximately 22.21 Earth days (6.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1712 AU.

Transit Fingerprint

Depth

0.046 %

Duration

7.323 h

Impact parameter b

0.757

Rp / R★

0.019975

Transit midpoint (BJD)

2,455,039.3592

Photometric dip

Transit produces a flux drop of 463 ppm lasting ≈ 7.32 h.

Extended Orbital Architecture

Planet / star radius ratio

0.019975

Semi-major axis / stellar radius

23.597

Impact parameter (b)

0.757

Transit mid-time (BJD)

2,455,039.3592

Angular separation (arcsec)

0.20600

Eq. Temperature

803K

(530 °C)

Insolation (S⊕)

160.61

Earth = 1.00

Earth Similarity (ESI)

0.286

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-521

Spectral Class

F-type yellow-white

Effective Temperature

6,406 K — hotter than the Sun (5,778 K)

Estimated Age

1.78 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.460 R☉

Stellar Mass

1.340 M☉

Metallicity [Fe/H]

0.25

Extended Stellar Properties

Surface gravity (log g)

4.240 dex

Stellar density

0.330 g/cm³

Systemic radial velocity

14.65 km/s

Metallicity ratio

[Fe/H]

Distance

830.64 parsec

Light-years 2,709.18 ly

V-band magnitude

12.94 mag

Voyager-speed travel 47,776,310 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

1.175 mas

Total Proper Motion

3.654 mas/yr

PM Right Ascension

-1.15 mas/yr

PM Declination

-3.47 mas/yr

Galactic Cartesian (pc)

x = 0.347 · y = -0.630 · z = 0.695

Equatorial (J2000)

RA 298.81638° · Dec 43.99802°

Galactic ℓ, b

78.617° · 8.090°

Ecliptic λ, β

318.944° · 62.626°

HTM-20 index

1985716214