Key parameters at a glance

A radius of 0.62 Earth radii
A mass of 0.17 Earth masses
Surface gravity around 0.45 g
An orbital period of 1.096 days
Semi-major axis 0.0146 AU
Distance from Earth 280.62 light-years
Earth Similarity Index 0.819
Travel time at Voyager 1 speed 4,948,734 years
Almost certainly tidally locked to its host star given the close orbit

K2-89 b Planet Profile

Physical Specs

Radius

0.62 R⊕

Radius (Jupiter)

0.055 R♃

Mass

0.17 M⊕

Mass (Jupiter)

0.001 M♃

Density

4.02 g/cm³

Surface Gravity

0.45 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.819

HZ Position Inner

Controversial No

Discovery

Year 2016

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#547of 570

top 95.8%

This planet

0.62R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

KOI-1843.03 0.61 R⊕ Kepler-1087 b 0.61 R⊕ Kepler-1877 b 0.62 R⊕

Metric	Earth	K2-89 b	Jupiter
Radius (R⊕)	1.00	0.62	11.21
Mass (M⊕)	1.00	0.17	317.83
Density (g/cm³)	5.51	4.02	1.33
Surface Gravity (g)	1.00	0.45	2.53
Insolation (S⊕)	1.00	78.00	0.037

Star Catalogue Identifiers

TIC

TIC 440687723

Gaia DR2

Gaia DR2 63206117414110848

Gaia DR3

Gaia DR3 63206117414110848

System

K2-89

Percentile among Rocky Terrestrial cohort

Radius 0.615 R⊕ · percentile 4 / cohort 570

Mass 0.170 M⊕ · percentile 3 / cohort 570

Orbital period 1.10 d · percentile 12 / cohort 567

Distance 86.04 pc · percentile 22 / cohort 566

ESI 0.819 · percentile 88 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

1.096 days

Semi-major axis

0.0146 AU

Eccentricity

0.150

Inclination

85.77 °

Year Length

A year here lasts approximately 1.10 Earth days (0.3% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0146 AU.

Transit Fingerprint

Depth

0.035 %

Duration

0.895 h

Rp / R★

0.017600

Transit midpoint (BJD)

2,457,066.0066

Photometric dip

Transit produces a flux drop of 346 ppm lasting ≈ 0.90 h.

Extended Orbital Architecture

Planet / star radius ratio

0.017600

Semi-major axis / stellar radius

7.360

Transit mid-time (BJD)

2,457,066.0066

Long. of periastron (ω)

51.29°

Angular separation (arcsec)

0.17000

Eq. Temperature

—

Insolation (S⊕)

78.00

Earth = 1.00

Earth Similarity (ESI)

0.819

0 = alien, 1 = Earth-identical

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

Discovery Paper

Primary reference

Crossfield et al. 2016

Instrument

Kepler CCD Array

Publication

2016-09

Observation locale

Space

Discovery cohort

Planets confirmed in 2016 at K2 (12 shown).

K2-72 d · Rocky Terrestrial K2-72 b · Rocky Terrestrial K2-91 b · Rocky Terrestrial K2-72 c · Rocky Terrestrial K2-102 b · Super-Earth K2-90 c · Super-Earth K2-72 e · Super-Earth K2-83 b · Rocky Terrestrial K2-88 b · Rocky Terrestrial K2-80 c · Super-Earth K2-83 c · Super-Earth K2-65 b · Super-Earth

Host System: K2-89

Spectral Class

M-type red dwarf

Effective Temperature

3,691 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.318 R☉

Stellar Mass

0.347 M☉

Metallicity [Fe/H]

—

Extended Stellar Properties

Surface gravity (log g)

4.965 dex

Stellar density

4.893 g/cm³

Systemic radial velocity

15.33 km/s

Distance

86.04 parsec

Light-years 280.62 ly

V-band magnitude

14.16 mag

Voyager-speed travel 4,948,734 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

11.594 mas

Total Proper Motion

96.360 mas/yr

PM Right Ascension

90.23 mas/yr

PM Declination

-33.83 mas/yr

Galactic Cartesian (pc)

x = 0.509 · y = 0.786 · z = 0.350

Equatorial (J2000)

RA 57.06712° · Dec 20.45949°

Galactic ℓ, b

169.552° · -25.997°

Ecliptic λ, β

59.374° · 0.453°

HTM-20 index

1503330393