Key parameters at a glance

A radius of 1.67 Earth radii
A mass of 3.45 Earth masses
Surface gravity around 1.23 g
An orbital period of 4.191 days
Semi-major axis 0.0488 AU
Equilibrium temperature 1,122 K (849 °C)
Distance from Earth 837.85 light-years
Earth Similarity Index 0.254
Travel time at Voyager 1 speed 14,775,526 years

K2-208 b Planet Profile

Physical Specs

Radius

1.67 R⊕

Radius (Jupiter)

0.149 R♃

Mass

3.45 M⊕

Mass (Jupiter)

0.011 M♃

Density

4.04 g/cm³

Surface Gravity

1.23 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.254

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

#448of 1176

top 38.0%

This planet

1.67R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-167 c 1.67 R⊕ K2-408 b 1.68 R⊕ TOI-1452 b 1.67 R⊕

Metric	Earth	K2-208 b	Jupiter
Radius (R⊕)	1.00	1.67	11.21
Mass (M⊕)	1.00	3.45	317.83
Density (g/cm³)	5.51	4.04	1.33
Surface Gravity (g)	1.00	1.23	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 399722652

Gaia DR2

Gaia DR2 2534388703049641472

Gaia DR3

Gaia DR3 2534388703049641472

System

K2-208

Percentile among Super-Earth cohort

Radius 1.675 R⊕ · percentile 62 / cohort 1176

Mass 3.450 M⊕ · percentile 56 / cohort 1176

Orbital period 4.19 d · percentile 33 / cohort 1164

Distance 256.89 pc · percentile 28 / cohort 1171

ESI 0.254 · percentile 24 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

4.191 days

Semi-major axis

0.0488 AU

Eccentricity

0.370

Inclination

86.94 °

Year Length

A year here lasts approximately 4.19 Earth days (1.1% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.0488 AU.

Transit Fingerprint

Depth

0.031 %

Duration

1.944 h

Impact parameter b

0.490

Rp / R★

0.017570

Transit midpoint (BJD)

2,457,430.0390

Photometric dip

Transit produces a flux drop of 309 ppm lasting ≈ 1.94 h.

Extended Orbital Architecture

Planet / star radius ratio

0.017570

Semi-major axis / stellar radius

12.030

Impact parameter (b)

0.490

Transit mid-time (BJD)

2,457,430.0390

Long. of periastron (ω)

-210.00°

Angular separation (arcsec)

0.19000

Eq. Temperature

1,122K

(849 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.254

0 = alien, 1 = Earth-identical

Insufficient insolation data — the dayside is scorched.

Discovery Paper

Primary reference

Mayo et al. 2018

Instrument

Kepler CCD Array

Publication

2018-03

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: K2-208

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,500 K — cooler than the Sun (5,778 K)

Estimated Age

6.10 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.872 R☉

Stellar Mass

0.881 M☉

Metallicity [Fe/H]

-0.06

Extended Stellar Properties

Surface gravity (log g)

4.503 dex

Stellar density

1.880 g/cm³

Systemic radial velocity

11.59 km/s

Metallicity ratio

[Fe/H]

Distance

256.89 parsec

Light-years 837.85 ly

V-band magnitude

12.58 mag

Voyager-speed travel 14,775,526 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

3.865 mas

Total Proper Motion

47.382 mas/yr

PM Right Ascension

-26.35 mas/yr

PM Declination

-39.38 mas/yr

Galactic Cartesian (pc)

x = 0.935 · y = 0.355 · z = 0.016

Equatorial (J2000)

RA 20.77898° · Dec 0.88901°

Galactic ℓ, b

139.422° · -60.964°

Ecliptic λ, β

19.528° · -7.288°

HTM-20 index

1062249162