Key parameters at a glance

A radius of 3.65 Earth radii
A mass of 12.90 Earth masses
Surface gravity around 0.97 g
An orbital period of 61.618 days
Semi-major axis 0.3020 AU
Equilibrium temperature 424 K (151 °C)
Distance from Earth 3,533.61 light-years
Earth Similarity Index 0.490
Travel time at Voyager 1 speed 62,315,151 years

Kepler-1128 b Planet Profile

Physical Specs

Radius

3.65 R⊕

Radius (Jupiter)

0.326 R♃

Mass

12.90 M⊕

Mass (Jupiter)

0.041 M♃

Density

1.46 g/cm³

Surface Gravity

0.97 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.490

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

#113of 1978

top 5.7%

This planet

3.65R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

WASP-47 d 3.65 R⊕ Kepler-967 c 3.65 R⊕ TOI-1231 b 3.65 R⊕

Metric	Earth	Kepler-1128 b	Jupiter
Radius (R⊕)	1.00	3.65	11.21
Mass (M⊕)	1.00	12.90	317.83
Density (g/cm³)	5.51	1.46	1.33
Surface Gravity (g)	1.00	0.97	2.53
Insolation (S⊕)	1.00	6.45	0.037

Star Catalogue Identifiers

TIC

TIC 137972889

Gaia DR2

Gaia DR2 2053124285963894784

Gaia DR3

Gaia DR3 2053124285963894784

System

Kepler-1128

Percentile among Sub-Neptune cohort

Radius 3.650 R⊕ · percentile 94 / cohort 1978

Mass 12.900 M⊕ · percentile 87 / cohort 1978

Orbital period 61.62 d · percentile 89 / cohort 1946

Distance 1,083.41 pc · percentile 83 / cohort 1975

ESI 0.490 · percentile 69 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

61.618 days

Semi-major axis

0.3020 AU

Eccentricity

0.000

Inclination

89.96 °

Year Length

A year here lasts approximately 61.62 Earth days (16.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.3020 AU.

Transit Fingerprint

Depth

0.135 %

Duration

3.752 h

Impact parameter b

0.091

Rp / R★

0.036584

Transit midpoint (BJD)

2,455,012.0788

Photometric dip

Transit produces a flux drop of 1,351 ppm lasting ≈ 3.75 h.

Extended Orbital Architecture

Planet / star radius ratio

0.036584

Semi-major axis / stellar radius

126.930

Impact parameter (b)

0.091

Transit mid-time (BJD)

2,455,012.0788

Angular separation (arcsec)

0.27900

Eq. Temperature

424K

(151 °C)

Insolation (S⊕)

6.45

Earth = 1.00

Earth Similarity (ESI)

0.490

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-1128

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,543 K — cooler than the Sun (5,778 K)

Estimated Age

4.57 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.910 R☉

Stellar Mass

0.940 M☉

Metallicity [Fe/H]

0.04

Extended Stellar Properties

Surface gravity (log g)

4.500 dex

Stellar density

10.190 g/cm³

Metallicity ratio

[Fe/H]

Distance

1,083.41 parsec

Light-years 3,533.61 ly

V-band magnitude

15.93 mag

Voyager-speed travel 62,315,151 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.896 mas

Total Proper Motion

9.080 mas/yr

PM Right Ascension

-1.51 mas/yr

PM Declination

-8.95 mas/yr

Galactic Cartesian (pc)

x = 0.303 · y = -0.711 · z = 0.635

Equatorial (J2000)

RA 293.06332° · Dec 39.40341°

Galactic ℓ, b

72.453° · 9.650°

Ecliptic λ, β

307.129° · 59.904°

HTM-20 index

1266344875