Key parameters at a glance

A radius of 1.16 Earth radii
A mass of 1.65 Earth masses
Surface gravity around 1.23 g
An orbital period of 2.219 days
Semi-major axis 0.0373 AU
Equilibrium temperature 769 K (496 °C)
Distance from Earth 234.98 light-years
Earth Similarity Index 0.414
Travel time at Voyager 1 speed 4,143,822 years
Almost certainly tidally locked to its host star given the close orbit

K2-122 b Planet Profile

Physical Specs

Radius

1.16 R⊕

Radius (Jupiter)

0.103 R♃

Mass

1.65 M⊕

Mass (Jupiter)

0.005 M♃

Density

5.81 g/cm³

Surface Gravity

1.23 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.414

HZ Position Inner

Controversial No

Discovery

Year 2017

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#147of 570

top 25.6%

This planet

1.16R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-363 b 1.16 R⊕ OGLE-2013-BLG-0341L B b 1.16 R⊕ Kepler-316 c 1.16 R⊕

Metric	Earth	K2-122 b	Jupiter
Radius (R⊕)	1.00	1.16	11.21
Mass (M⊕)	1.00	1.65	317.83
Density (g/cm³)	5.51	5.81	1.33
Surface Gravity (g)	1.00	1.23	2.53
Insolation (S⊕)	1.00	79.90	0.037

Star Catalogue Identifiers

TIC

TIC 14635562

Gaia DR2

Gaia DR2 663843343706623232

Gaia DR3

Gaia DR3 663843343706623232

System

K2-122

Percentile among Rocky Terrestrial cohort

Radius 1.160 R⊕ · percentile 73 / cohort 570

Mass 1.650 M⊕ · percentile 66 / cohort 570

Orbital period 2.22 d · percentile 24 / cohort 567

Distance 72.04 pc · percentile 21 / cohort 566

ESI 0.414 · percentile 61 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

2.219 days

Semi-major axis

0.0373 AU

Eccentricity

0.210

Inclination

86.39 °

Year Length

A year here lasts approximately 2.22 Earth days (0.6% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0373 AU.

Transit Fingerprint

Depth

0.043 %

Duration

1.236 h

Impact parameter b

0.430

Rp / R★

0.018000

Transit midpoint (BJD)

2,457,141.8300

Photometric dip

Transit produces a flux drop of 432 ppm lasting ≈ 1.24 h.

Extended Orbital Architecture

Planet / star radius ratio

0.018000

Semi-major axis / stellar radius

13.610

Impact parameter (b)

0.430

Transit mid-time (BJD)

2,457,141.8300

Long. of periastron (ω)

60.80°

Angular separation (arcsec)

0.51800

Eq. Temperature

769K

(496 °C)

Insolation (S⊕)

79.90

Earth = 1.00

Earth Similarity (ESI)

0.414

0 = alien, 1 = Earth-identical

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

Discovery Paper

Primary reference

Dressing et al. 2017

Instrument

Kepler CCD Array

Publication

2017-11

Observation locale

Space

Discovery cohort

Planets confirmed in 2017 at K2 (12 shown).

K2-129 b · Rocky Terrestrial K2-130 b · Super-Earth K2-133 b · Super-Earth K2-128 b · Super-Earth K2-133 c · Super-Earth K2-116 b · Rocky Terrestrial K2-125 b · Sub-Neptune K2-118 b · Sub-Neptune K2-136 d · Super-Earth K2-123 b · Sub-Neptune K2-136 c · Sub-Neptune K2-124 b · Sub-Neptune

Host System: K2-122

Spectral Class

M-type red dwarf

Effective Temperature

4,009 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.590 R☉

Stellar Mass

0.630 M☉

Metallicity [Fe/H]

0.32

Extended Stellar Properties

Surface gravity (log g)

4.690 dex

Stellar density

3.652 g/cm³

Systemic radial velocity

-14.35 km/s

Metallicity ratio

[Fe/H]

Distance

72.04 parsec

Light-years 234.98 ly

V-band magnitude

13.11 mag

Voyager-speed travel 4,143,822 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

13.852 mas

Total Proper Motion

57.885 mas/yr

PM Right Ascension

-21.93 mas/yr

PM Declination

-53.57 mas/yr

Galactic Cartesian (pc)

x = -0.557 · y = 0.754 · z = 0.348

Equatorial (J2000)

RA 126.47622° · Dec 20.35934°

Galactic ℓ, b

203.781° · 29.532°

Ecliptic λ, β

123.876° · 1.107°

HTM-20 index

-210741256