Key parameters at a glance

A radius of 3.00 Earth radii
A mass of 9.27 Earth masses
Surface gravity around 1.03 g
An orbital period of 19.092 days
Semi-major axis 0.1490 AU
Equilibrium temperature 831 K (558 °C)
Distance from Earth 2,158.74 light-years
Earth Similarity Index 0.283
Travel time at Voyager 1 speed 38,069,351 years

K2-258 b Planet Profile

Physical Specs

Radius

3.00 R⊕

Radius (Jupiter)

0.268 R♃

Mass

9.27 M⊕

Mass (Jupiter)

0.029 M♃

Density

1.89 g/cm³

Surface Gravity

1.03 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.283

HZ Position Unknown

Controversial No

Discovery

Year 2018

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#521of 1978

top 26.3%

This planet

3.00R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-338 d 3.00 R⊕ HD 3167 c 3.00 R⊕ HIP 94235 b 3.00 R⊕

Metric	Earth	K2-258 b	Jupiter
Radius (R⊕)	1.00	3.00	11.21
Mass (M⊕)	1.00	9.27	317.83
Density (g/cm³)	5.51	1.89	1.33
Surface Gravity (g)	1.00	1.03	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 130634730

Gaia DR2

Gaia DR2 3695568295896473856

Gaia DR3

Gaia DR3 3695568295896473856

System

K2-258

Percentile among Sub-Neptune cohort

Radius 3.000 R⊕ · percentile 73 / cohort 1978

Mass 9.270 M⊕ · percentile 67 / cohort 1978

Orbital period 19.09 d · percentile 60 / cohort 1946

Distance 661.87 pc · percentile 57 / cohort 1975

ESI 0.283 · percentile 24 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

19.092 days

Semi-major axis

0.1490 AU

Eccentricity

—

Inclination

— °

Year Length

A year here lasts approximately 19.09 Earth days (5.2% of a terrestrial year) at a mean orbital distance of 0.1490 AU.

Transit Fingerprint

Depth

0.049 %

Duration

6.000 h

Impact parameter b

0.370

Rp / R★

0.021000

Transit midpoint (BJD)

2,457,586.2928

Photometric dip

Transit produces a flux drop of 490 ppm lasting ≈ 6.00 h.

Extended Orbital Architecture

Planet / star radius ratio

0.021000

Semi-major axis / stellar radius

21.500

Impact parameter (b)

0.370

Transit mid-time (BJD)

2,457,586.2928

Angular separation (arcsec)

0.22500

Eq. Temperature

831K

(558 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.283

0 = alien, 1 = Earth-identical

Insufficient insolation data — the surface is too hot to retain surface water.

Discovery Paper

Primary reference

Livingston et al. 2018

Instrument

Kepler CCD Array

Publication

2018-08

Observation locale

Space

Discovery cohort

Planets confirmed in 2018 at K2 (12 shown).

K2-190 c · Rocky Terrestrial K2-183 b · Rocky Terrestrial K2-209 b · Rocky Terrestrial K2-210 b · Rocky Terrestrial K2-165 b · Super-Earth K2-169 b · Super-Earth K2-148 b · Super-Earth K2-219 b · Super-Earth K2-190 b · Super-Earth K2-200 b · Super-Earth K2-201 b · Super-Earth K2-170 b · Super-Earth

Host System: K2-258

Spectral Class

F-type yellow-white

Effective Temperature

6,351 K — hotter than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

1.310 R☉

Stellar Mass

1.210 M☉

Metallicity [Fe/H]

0.01

Extended Stellar Properties

Surface gravity (log g)

4.290 dex

Stellar density

0.566 g/cm³

Metallicity ratio

[Fe/H]

Distance

661.87 parsec

Light-years 2,158.74 ly

V-band magnitude

13.36 mag

Voyager-speed travel 38,069,351 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

1.482 mas

Total Proper Motion

15.446 mas/yr

PM Right Ascension

14.96 mas/yr

PM Declination

-3.84 mas/yr

Galactic Cartesian (pc)

x = -0.991 · y = -0.133 · z = -0.020

Equatorial (J2000)

RA 187.63140° · Dec -1.16092°

Galactic ℓ, b

292.008° · 61.267°

Ecliptic λ, β

187.463° · 1.961°

HTM-20 index

-416810819