Confirmed Exoplanet Discovered 2018

K2-268 b

A super-earth orbiting the k-type orange K2-268, located approximately 1,069.1 light-years from Earth.

Key parameters at a glance

  • A radius of 1.50 Earth radii
  • A mass of 2.86 Earth masses
  • Surface gravity around 1.27 g
  • An orbital period of 2.152 days
  • Semi-major axis 0.0308 AU
  • Equilibrium temperature 1,136 K (863 °C)
  • Distance from Earth 1,069.08 light-years
  • Earth Similarity Index 0.260
  • Travel time at Voyager 1 speed 18,853,294 years
  • Almost certainly tidally locked to its host star given the close orbit

4 siblings around K2-268

K2-268 b shares its host star with 4 other confirmed planets. Side-by-side measurements below.

Planet Type Radius (R⊕) Mass (M⊕) Period (d) Eq. T (K) Year
K2-268 b this Super-Earth 1.50 2.86 2.152 1,136 2018
K2-268 d Super-Earth 1.49 2.83 4.529 888 2021
K2-268 e Super-Earth 1.33 2.33 6.131 801 2021
K2-268 c Sub-Neptune 2.69 7.70 9.328 696 2018
K2-268 f Sub-Neptune 2.23 5.60 26.271 492 2021

K2-268 b Planet Profile

Physical Specs

Radius
1.50 R⊕
Radius (Jupiter)
0.134 R♃
Mass
2.86 M⊕
Mass (Jupiter)
0.009 M♃
Density
4.66 g/cm³
Surface Gravity
1.27 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.260
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

#748of 1176

top 63.5%

This planet

1.50R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Metric Earth K2-268 b Jupiter
Radius (R⊕)1.001.5011.21
Mass (M⊕)1.002.86317.83
Density (g/cm³)5.514.661.33
Surface Gravity (g)1.001.272.53
Insolation (S⊕)1.000.037

Star Catalogue Identifiers

TIC

TIC 444037742

Gaia DR2

Gaia DR2 604743013163971072

Gaia DR3

Gaia DR3 604743013163971072

System

K2-268

Percentile among Super-Earth cohort

Radius 1.500 R⊕ · percentile 35 / cohort 1176
Mass 2.860 M⊕ · percentile 33 / cohort 1176
Orbital period 2.15 d · percentile 13 / cohort 1164
Distance 327.78 pc · percentile 34 / cohort 1171
ESI 0.260 · percentile 26 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period
2.152 days
Semi-major axis
0.0308 AU
Eccentricity
Inclination
°

Year Length

A year here lasts approximately 2.15 Earth days (0.6% of a terrestrial year) at a mean orbital distance of 0.0308 AU.

Transit Fingerprint

Depth

0.040 %

Duration

1.970 h

Impact parameter b

0.420

Rp / R★

0.017500

Transit midpoint (BJD)

2,457,143.6543

Photometric dip

Transit produces a flux drop of 398 ppm lasting ≈ 1.97 h.

Extended Orbital Architecture

Planet / star radius ratio

0.017500

Semi-major axis / stellar radius

7.760

Impact parameter (b)

0.420

Transit mid-time (BJD)

2,457,143.6543

Angular separation (arcsec)

0.09400

Eq. Temperature

1,136K

(863 °C)

Insolation (S⊕)

Earth = 1.00

Earth Similarity (ESI)

0.260

0 = alien, 1 = Earth-identical

Insufficient insolation data — the dayside is scorched. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Livingston et al. 2018

Instrument

Kepler CCD Array

Publication

2018-12

Observation locale

Space

Host System: K2-268

Spectral Class

K-type orange

Effective Temperature

5,106 K — cooler than the Sun (5,778 K)

Estimated Age

Stellar Radius

0.780 R☉

Stellar Mass

0.840 M☉

Metallicity [Fe/H]

0.03

Extended Stellar Properties

Surface gravity (log g)

4.580 dex

Stellar density

2.299 g/cm³

Rotation period

24.87 days

Metallicity ratio

[Fe/H]

Distance
327.78 parsec
Light-years 1,069.08 ly
V-band magnitude
13.85 mag
Voyager-speed travel 18,853,294 yr

Multi-band Host Photometry — 17 bands

8.816.316.34U14.78B13.85V13.56Gaia13.54Kepler12.99TESS15.41Sloan g13.62Sloan r15.04Sloan i13.77Sloan z12.16J11.72H11.64K11.58W111.65W211.81W38.82W4

Astrometric Data

Parallax

3.022 mas

Total Proper Motion

8.195 mas/yr

PM Right Ascension

-8.19 mas/yr

PM Declination

0.12 mas/yr

Galactic Cartesian (pc)

x = -0.676 · y = 0.707 · z = 0.205

Equatorial (J2000)

RA 133.70949° · Dec 11.84827°

Galactic ℓ, b

216.073° · 32.703°

Ecliptic λ, β

132.779° · -5.338°

HTM-20 index

-1890003543

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