Key parameters at a glance

A radius of 1.68 Earth radii
A mass of 3.46 Earth masses
Surface gravity around 1.23 g
An orbital period of 2.399 days
Distance from Earth 1,039.82 light-years
Earth Similarity Index 0.850
Travel time at Voyager 1 speed 18,337,188 years

K2-221 b Planet Profile

Physical Specs

Radius

1.68 R⊕

Radius (Jupiter)

0.150 R♃

Mass

3.46 M⊕

Mass (Jupiter)

0.011 M♃

Density

4.02 g/cm³

Surface Gravity

1.23 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.850

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

#446of 1176

top 37.8%

This planet

1.68R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-1449 b 1.68 R⊕ Kepler-188 b 1.68 R⊕ Kepler-795 b 1.68 R⊕

Metric	Earth	K2-221 b	Jupiter
Radius (R⊕)	1.00	1.68	11.21
Mass (M⊕)	1.00	3.46	317.83
Density (g/cm³)	5.51	4.02	1.33
Surface Gravity (g)	1.00	1.23	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 257801011

Gaia DR2

Gaia DR2 2582898606311167872

Gaia DR3

Gaia DR3 2582898606311167872

System

K2-221

Percentile among Super-Earth cohort

Radius 1.679 R⊕ · percentile 62 / cohort 1176

Mass 3.460 M⊕ · percentile 56 / cohort 1176

Orbital period 2.40 d · percentile 15 / cohort 1164

Distance 318.81 pc · percentile 33 / cohort 1171

ESI 0.850 · percentile 93 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

2.399 days

Semi-major axis

— AU

Eccentricity

—

Inclination

85.45 °

Year Length

A year here lasts approximately 2.40 Earth days (0.7% of a terrestrial year).

Transit Fingerprint

Depth

0.031 %

Duration

2.503 h

Rp / R★

0.016243

Transit midpoint (BJD)

2,457,395.3558

Photometric dip

Transit produces a flux drop of 312 ppm lasting ≈ 2.50 h.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.850

0 = alien, 1 = Earth-identical

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: K2-221

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,716 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.948 R☉

Stellar Mass

1.011 M☉

Metallicity [Fe/H]

0.13

Extended Stellar Properties

Surface gravity (log g)

4.570 dex

Stellar density

1.286 g/cm³

Systemic radial velocity

8.70 km/s

Metallicity ratio

[Fe/H]

Distance

318.81 parsec

Light-years 1,039.82 ly

V-band magnitude

12.57 mag

Voyager-speed travel 18,337,188 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

3.109 mas

Total Proper Motion

17.370 mas/yr

PM Right Ascension

11.05 mas/yr

PM Declination

13.40 mas/yr

Galactic Cartesian (pc)

x = 0.943 · y = 0.282 · z = 0.177

Equatorial (J2000)

RA 16.65503° · Dec 10.18974°

Galactic ℓ, b

129.076° · -52.501°

Ecliptic λ, β

19.240° · 2.872°

HTM-20 index

-1420920881