Key parameters at a glance

A radius of 2.00 Earth radii
A mass of 4.67 Earth masses
Surface gravity around 1.16 g
An orbital period of 11.025 days
Semi-major axis 0.0749 AU
Equilibrium temperature 734 K (461 °C)
Distance from Earth 245.17 light-years
Earth Similarity Index 0.375
Travel time at Voyager 1 speed 4,323,616 years
Almost certainly tidally locked to its host star given the close orbit

3 siblings around K2-133

K2-133 d shares its host star with 3 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
K2-133 b	Super-Earth	1.34	2.36	3.071	—	2017
K2-133 c	Super-Earth	1.60	3.20	4.868	—	2017
K2-133 d this	Sub-Neptune	2.00	4.67	11.025	734	2017
K2-133 e	Super-Earth	1.73	3.64	26.584	296	2019

K2-133 d Planet Profile

Physical Specs

Radius

2.00 R⊕

Radius (Jupiter)

0.179 R♃

Mass

4.67 M⊕

Mass (Jupiter)

0.015 M♃

Density

3.19 g/cm³

Surface Gravity

1.16 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.375

HZ Position Inner

Controversial No

Discovery

Year 2017

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#1953of 1978

top 98.7%

This planet

2.00R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

HR 858 b 2.00 R⊕ HR 858 d 2.00 R⊕ Kepler-238 f 2.00 R⊕

Metric	Earth	K2-133 d	Jupiter
Radius (R⊕)	1.00	2.00	11.21
Mass (M⊕)	1.00	4.67	317.83
Density (g/cm³)	5.51	3.19	1.33
Surface Gravity (g)	1.00	1.16	2.53
Insolation (S⊕)	1.00	48.33	0.037

Star Catalogue Identifiers

TIC

TIC 150096001

Gaia DR2

Gaia DR2 148080473682357376

Gaia DR3

Gaia DR3 148080473682357376

System

K2-133

Percentile among Sub-Neptune cohort

Radius 2.003 R⊕ · percentile 1 / cohort 1978

Mass 4.670 M⊕ · percentile 3 / cohort 1978

Orbital period 11.02 d · percentile 38 / cohort 1946

Distance 75.17 pc · percentile 16 / cohort 1975

ESI 0.375 · percentile 47 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

11.025 days

Semi-major axis

0.0749 AU

Eccentricity

—

Inclination

89.40 °

Year Length

A year here lasts approximately 11.02 Earth days (3.0% of a terrestrial year) at a mean orbital distance of 0.0749 AU.

Transit Fingerprint

Depth

0.190 %

Duration

2.320 h

Impact parameter b

0.370

Rp / R★

0.040400

Transit midpoint (BJD)

2,457,826.1709

Photometric dip

Transit produces a flux drop of 1,900 ppm lasting ≈ 2.32 h.

Extended Orbital Architecture

Planet / star radius ratio

0.040400

Impact parameter (b)

0.370

Transit mid-time (BJD)

2,457,826.1709

Angular separation (arcsec)

0.99600

Eq. Temperature

734K

(461 °C)

Insolation (S⊕)

48.33

Earth = 1.00

Earth Similarity (ESI)

0.375

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Wells et al. 2018

Instrument

Kepler CCD Array

Publication

2018-01

Observation locale

Space

Discovery cohort

Planets confirmed in 2017 at K2 (12 shown).

K2-129 b · Rocky Terrestrial K2-130 b · Super-Earth K2-133 b · Super-Earth K2-128 b · Super-Earth K2-133 c · Super-Earth K2-116 b · Rocky Terrestrial K2-125 b · Sub-Neptune K2-118 b · Sub-Neptune K2-136 d · Super-Earth K2-123 b · Sub-Neptune K2-136 c · Sub-Neptune K2-124 b · Sub-Neptune

Host System: K2-133

Spectral Class

M-type red dwarf

Effective Temperature

3,655 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.455 R☉

Stellar Mass

0.461 M☉

Metallicity [Fe/H]

—

Extended Stellar Properties

Surface gravity (log g)

4.770 dex

Stellar density

6.630 g/cm³

Systemic radial velocity

107.20 km/s

Distance

75.17 parsec

Light-years 245.17 ly

V-band magnitude

14.07 mag

Voyager-speed travel 4,323,616 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

13.274 mas

Total Proper Motion

191.359 mas/yr

PM Right Ascension

185.66 mas/yr

PM Declination

-46.36 mas/yr

Galactic Cartesian (pc)

x = 0.308 · y = 0.852 · z = 0.423

Equatorial (J2000)

RA 70.14938° · Dec 25.00981°

Galactic ℓ, b

174.754° · -14.068°

Ecliptic λ, β

72.052° · 2.799°

HTM-20 index

-1995439910