Key parameters at a glance

A radius of 1.10 Earth radii
A mass of 1.37 Earth masses
Surface gravity around 1.13 g
An orbital period of 1.420 days
Semi-major axis 0.0164 AU
Distance from Earth 204.10 light-years
Earth Similarity Index 0.973
Travel time at Voyager 1 speed 3,599,366 years
Almost certainly tidally locked to its host star given the close orbit

K2-91 b Planet Profile

Physical Specs

Radius

1.10 R⊕

Radius (Jupiter)

0.098 R♃

Mass

1.37 M⊕

Mass (Jupiter)

0.004 M♃

Density

5.66 g/cm³

Surface Gravity

1.13 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.973

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

#224of 570

top 39.1%

This planet

1.10R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-392 c 1.10 R⊕ Kepler-59 b 1.10 R⊕ K2-239 d 1.10 R⊕

Metric	Earth	K2-91 b	Jupiter
Radius (R⊕)	1.00	1.10	11.21
Mass (M⊕)	1.00	1.37	317.83
Density (g/cm³)	5.51	5.66	1.33
Surface Gravity (g)	1.00	1.13	2.53
Insolation (S⊕)	1.00	46.00	0.037

Star Catalogue Identifiers

TIC

TIC 56520147

Gaia DR2

Gaia DR2 149858216482858112

Gaia DR3

Gaia DR3 149858216482858112

System

K2-91

Percentile among Rocky Terrestrial cohort

Radius 1.100 R⊕ · percentile 59 / cohort 570

Mass 1.370 M⊕ · percentile 54 / cohort 570

Orbital period 1.42 d · percentile 15 / cohort 567

Distance 62.58 pc · percentile 19 / cohort 566

ESI 0.973 · percentile 96 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

1.420 days

Semi-major axis

0.0164 AU

Eccentricity

0.090

Inclination

88.62 °

Year Length

A year here lasts approximately 1.42 Earth days (0.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0164 AU.

Transit Fingerprint

Depth

0.157 %

Duration

0.945 h

Rp / R★

0.035200

Transit midpoint (BJD)

2,457,065.4319

Photometric dip

Transit produces a flux drop of 1,565 ppm lasting ≈ 0.95 h.

Extended Orbital Architecture

Planet / star radius ratio

0.035200

Semi-major axis / stellar radius

11.190

Transit mid-time (BJD)

2,457,065.4319

Long. of periastron (ω)

-23.36°

Angular separation (arcsec)

0.26200

Eq. Temperature

—

Insolation (S⊕)

46.00

Earth = 1.00

Earth Similarity (ESI)

0.973

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 K2-72 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 K2-68 b · Super-Earth

Host System: K2-91

Spectral Class

M-type red dwarf

Effective Temperature

3,622 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.284 R☉

Stellar Mass

0.292 M☉

Metallicity [Fe/H]

—

Distance

62.58 parsec

Light-years 204.10 ly

V-band magnitude

15.62 mag

Voyager-speed travel 3,599,366 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

15.952 mas

Total Proper Motion

99.250 mas/yr

PM Right Ascension

43.01 mas/yr

PM Declination

-89.45 mas/yr

Galactic Cartesian (pc)

x = 0.411 · y = 0.814 · z = 0.410

Equatorial (J2000)

RA 63.21823° · Dec 24.20472°

Galactic ℓ, b

171.030° · -19.325°

Ecliptic λ, β

65.694° · 2.997°

HTM-20 index

2721449