Key parameters at a glance

A radius of 2.55 Earth radii
A mass of 7.05 Earth masses
Surface gravity around 1.08 g
An orbital period of 69.896 days
Semi-major axis 0.3200 AU
Equilibrium temperature 442 K (169 °C)
Distance from Earth 2,473.24 light-years
Earth Similarity Index 0.548
Travel time at Voyager 1 speed 43,615,602 years

Kepler-1681 b Planet Profile

Physical Specs

Radius

2.55 R⊕

Radius (Jupiter)

0.228 R♃

Mass

7.05 M⊕

Mass (Jupiter)

0.022 M♃

Density

2.33 g/cm³

Surface Gravity

1.08 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.548

HZ Position Inner

Controversial No

Discovery

Year 2020

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#1101of 1978

top 55.6%

This planet

2.55R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-1836 b 2.55 R⊕ TOI-5726.01 2.55 R⊕ K2-80 d 2.55 R⊕

Metric	Earth	Kepler-1681 b	Jupiter
Radius (R⊕)	1.00	2.55	11.21
Mass (M⊕)	1.00	7.05	317.83
Density (g/cm³)	5.51	2.33	1.33
Surface Gravity (g)	1.00	1.08	2.53
Insolation (S⊕)	1.00	5.33	0.037

Star Catalogue Identifiers

TIC

TIC 272602477

Gaia DR2

Gaia DR2 2080316995223800960

Gaia DR3

Gaia DR3 2080316995223800960

System

Kepler-1681

Percentile among Sub-Neptune cohort

Radius 2.553 R⊕ · percentile 44 / cohort 1978

Mass 7.050 M⊕ · percentile 41 / cohort 1978

Orbital period 69.90 d · percentile 90 / cohort 1946

Distance 758.30 pc · percentile 62 / cohort 1975

ESI 0.548 · percentile 76 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

69.896 days

Semi-major axis

0.3200 AU

Eccentricity

0.000

Inclination

89.08 °

Year Length

A year here lasts approximately 69.90 Earth days (19.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.3200 AU.

Transit Fingerprint

Depth

0.055 %

Duration

5.276 h

Impact parameter b

0.515

Rp / R★

0.022211

Transit midpoint (BJD)

2,454,993.6681

Photometric dip

Transit produces a flux drop of 548 ppm lasting ≈ 5.28 h.

Extended Orbital Architecture

Planet / star radius ratio

0.022211

Semi-major axis / stellar radius

54.600

Impact parameter (b)

0.515

Transit mid-time (BJD)

2,454,993.6681

Angular separation (arcsec)

0.42200

Eq. Temperature

442K

(169 °C)

Insolation (S⊕)

5.33

Earth = 1.00

Earth Similarity (ESI)

0.548

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

Armstrong et al. 2021

Instrument

Kepler CCD Array

Publication

2021-07

Observation locale

Space

Discovery cohort

Planets confirmed in 2020 at Kepler (12 shown).

Kepler-1649 c · Rocky Terrestrial Kepler-1701 b · Sub-Neptune Kepler-1690 b · Sub-Neptune Kepler-1700 b · Sub-Neptune Kepler-1684 b · Sub-Neptune Kepler-1678 b · Sub-Neptune Kepler-598 c · Sub-Neptune Kepler-1661 b · Sub-Neptune Kepler-1663 b · Sub-Neptune Kepler-1672 b · Sub-Neptune Kepler-1702 b · Super-Earth Kepler-1674 b · Sub-Neptune

Host System: Kepler-1681

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,756 K — cooler than the Sun (5,778 K)

Estimated Age

3.30 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.759 R☉

Stellar Mass

0.893 M☉

Metallicity [Fe/H]

0.11

Extended Stellar Properties

Surface gravity (log g)

4.538 dex

Stellar density

3.450 g/cm³

Metallicity ratio

[M/H]

Distance

758.30 parsec

Light-years 2,473.24 ly

V-band magnitude

14.65 mag

Voyager-speed travel 43,615,602 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

1.533 mas

Total Proper Motion

10.942 mas/yr

PM Right Ascension

-4.19 mas/yr

PM Declination

10.11 mas/yr

Galactic Cartesian (pc)

x = 0.310 · y = -0.616 · z = 0.724

Equatorial (J2000)

RA 296.69728° · Dec 46.37170°

Galactic ℓ, b

79.972° · 10.555°

Ecliptic λ, β

318.148° · 65.409°

HTM-20 index

-2096412039