Key parameters at a glance

A radius of 2.87 Earth radii
A mass of 8.60 Earth masses
Surface gravity around 1.04 g
An orbital period of 51.301 days
Semi-major axis 0.2716 AU
Equilibrium temperature 492 K (219 °C)
Distance from Earth 3,047.90 light-years
Earth Similarity Index 0.477
Travel time at Voyager 1 speed 53,749,629 years

Kepler-921 b Planet Profile

Physical Specs

Radius

2.87 R⊕

Radius (Jupiter)

0.256 R♃

Mass

8.60 M⊕

Mass (Jupiter)

0.027 M♃

Density

2.00 g/cm³

Surface Gravity

1.04 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.477

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

#659of 1978

top 33.3%

This planet

2.87R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-297 b 2.87 R⊕ Kepler-880 c 2.87 R⊕ Kepler-11 c 2.87 R⊕

Metric	Earth	Kepler-921 b	Jupiter
Radius (R⊕)	1.00	2.87	11.21
Mass (M⊕)	1.00	8.60	317.83
Density (g/cm³)	5.51	2.00	1.33
Surface Gravity (g)	1.00	1.04	2.53
Insolation (S⊕)	1.00	15.01	0.037

Star Catalogue Identifiers

TIC

TIC 48448706

Gaia DR2

Gaia DR2 2132177282208543872

Gaia DR3

Gaia DR3 2132177282208543872

System

Kepler-921

Percentile among Sub-Neptune cohort

Radius 2.870 R⊕ · percentile 66 / cohort 1978

Mass 8.600 M⊕ · percentile 61 / cohort 1978

Orbital period 51.30 d · percentile 86 / cohort 1946

Distance 934.49 pc · percentile 74 / cohort 1975

ESI 0.477 · percentile 67 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

51.301 days

Semi-major axis

0.2716 AU

Eccentricity

0.000

Inclination

90.00 °

Year Length

A year here lasts approximately 51.30 Earth days (14.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2716 AU.

Transit Fingerprint

Depth

0.058 %

Duration

6.987 h

Impact parameter b

0.928

Rp / R★

0.028605

Transit midpoint (BJD)

2,454,986.5365

Photometric dip

Transit produces a flux drop of 581 ppm lasting ≈ 6.99 h.

Extended Orbital Architecture

Planet / star radius ratio

0.028605

Semi-major axis / stellar radius

74.620

Impact parameter (b)

0.928

Transit mid-time (BJD)

2,454,986.5365

Angular separation (arcsec)

0.29100

Eq. Temperature

492K

(219 °C)

Insolation (S⊕)

15.01

Earth = 1.00

Earth Similarity (ESI)

0.477

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-921

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,663 K — cooler than the Sun (5,778 K)

Estimated Age

4.27 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.910 R☉

Stellar Mass

0.930 M☉

Metallicity [Fe/H]

-0.12

Extended Stellar Properties

Surface gravity (log g)

4.500 dex

Stellar density

2.987 g/cm³

Metallicity ratio

[Fe/H]

Distance

934.49 parsec

Light-years 3,047.90 ly

V-band magnitude

14.85 mag

Voyager-speed travel 53,749,629 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

1.041 mas

Total Proper Motion

11.240 mas/yr

PM Right Ascension

4.14 mas/yr

PM Declination

-10.45 mas/yr

Galactic Cartesian (pc)

x = 0.165 · y = -0.632 · z = 0.757

Equatorial (J2000)

RA 284.61623° · Dec 49.19074°

Galactic ℓ, b

79.198° · 19.105°

Ecliptic λ, β

300.571° · 71.082°

HTM-20 index

-419161922