Key parameters at a glance

A radius of 2.32 Earth radii
A mass of 5.99 Earth masses
Surface gravity around 1.11 g
An orbital period of 15.480 days
Semi-major axis 0.1271 AU
Equilibrium temperature 795 K (522 °C)
Distance from Earth 1,358.30 light-years
Earth Similarity Index 0.328
Travel time at Voyager 1 speed 23,953,610 years

K2-259 b Planet Profile

Physical Specs

Radius

2.32 R⊕

Radius (Jupiter)

0.207 R♃

Mass

5.99 M⊕

Mass (Jupiter)

0.019 M♃

Density

2.64 g/cm³

Surface Gravity

1.11 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.328

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

#1469of 1978

top 74.2%

This planet

2.32R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-321 c 2.32 R⊕ K2-28 b 2.32 R⊕ Kepler-1208 b 2.32 R⊕

Metric	Earth	K2-259 b	Jupiter
Radius (R⊕)	1.00	2.32	11.21
Mass (M⊕)	1.00	5.99	317.83
Density (g/cm³)	5.51	2.64	1.33
Surface Gravity (g)	1.00	1.11	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 377259959

Gaia DR2

Gaia DR2 3700295641843380224

Gaia DR3

Gaia DR3 3700295641843380224

System

K2-259

Percentile among Sub-Neptune cohort

Radius 2.320 R⊕ · percentile 25 / cohort 1978

Mass 5.990 M⊕ · percentile 24 / cohort 1978

Orbital period 15.48 d · percentile 51 / cohort 1946

Distance 416.46 pc · percentile 42 / cohort 1975

ESI 0.328 · percentile 34 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

15.480 days

Semi-major axis

0.1271 AU

Eccentricity

—

Inclination

89.03 °

Year Length

A year here lasts approximately 15.48 Earth days (4.2% of a terrestrial year) at a mean orbital distance of 0.1271 AU.

Transit Fingerprint

Depth

0.037 %

Duration

4.200 h

Impact parameter b

0.410

Rp / R★

0.018900

Transit midpoint (BJD)

2,457,585.7094

Photometric dip

Transit produces a flux drop of 370 ppm lasting ≈ 4.20 h.

Extended Orbital Architecture

Planet / star radius ratio

0.018900

Semi-major axis / stellar radius

29.900

Impact parameter (b)

0.410

Transit mid-time (BJD)

2,457,585.7094

Angular separation (arcsec)

0.30500

Eq. Temperature

795K

(522 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.328

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: K2-259

Spectral Class

F-type yellow-white

Effective Temperature

6,059 K — hotter than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

1.130 R☉

Stellar Mass

1.140 M☉

Metallicity [Fe/H]

0.16

Extended Stellar Properties

Surface gravity (log g)

4.390 dex

Stellar density

1.007 g/cm³

Rotational v·sin i

5.23 km/s

Metallicity ratio

[Fe/H]

Distance

416.46 parsec

Light-years 1,358.30 ly

V-band magnitude

12.51 mag

Voyager-speed travel 23,953,610 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

2.373 mas

Total Proper Motion

3.494 mas/yr

PM Right Ascension

1.84 mas/yr

PM Declination

2.97 mas/yr

Galactic Cartesian (pc)

x = -0.993 · y = -0.118 · z = 0.027

Equatorial (J2000)

RA 186.80269° · Dec 1.56686°

Galactic ℓ, b

289.117° · 63.787°

Ecliptic λ, β

185.621° · 4.140°

HTM-20 index

-1460189561