Confirmed Exoplanet Discovered 2018

K2-270 c

A sub-neptune orbiting the k-type orange K2-270, located approximately 914.9 light-years from Earth.

Key parameters at a glance

  • A radius of 2.95 Earth radii
  • A mass of 9.01 Earth masses
  • Surface gravity around 1.04 g
  • An orbital period of 4.400 days
  • Semi-major axis 0.0497 AU
  • Equilibrium temperature 848 K (575 °C)
  • Distance from Earth 914.93 light-years
  • Earth Similarity Index 0.279
  • Travel time at Voyager 1 speed 16,134,724 years
  • Almost certainly tidally locked to its host star given the close orbit

1 sibling around K2-270

K2-270 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet Type Radius (R⊕) Mass (M⊕) Period (d) Eq. T (K) Year
K2-270 b Super-Earth 1.38 2.48 1.543 1,203 2018
K2-270 c this Sub-Neptune 2.95 9.01 4.400 848 2018

K2-270 c Planet Profile

Physical Specs

Radius
2.95 R⊕
Radius (Jupiter)
0.263 R♃
Mass
9.01 M⊕
Mass (Jupiter)
0.028 M♃
Density
1.93 g/cm³
Surface Gravity
1.04 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.279
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

#557of 1978

top 28.1%

This planet

2.95R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Metric Earth K2-270 c Jupiter
Radius (R⊕)1.002.9511.21
Mass (M⊕)1.009.01317.83
Density (g/cm³)5.511.931.33
Surface Gravity (g)1.001.042.53
Insolation (S⊕)1.000.037

Star Catalogue Identifiers

TIC

TIC 293375721

Gaia DR2

Gaia DR2 608395625151767680

Gaia DR3

Gaia DR3 608395625151767680

System

K2-270

Percentile among Sub-Neptune cohort

Radius 2.950 R⊕ · percentile 71 / cohort 1978
Mass 9.010 M⊕ · percentile 65 / cohort 1978
Orbital period 4.40 d · percentile 10 / cohort 1946
Distance 280.52 pc · percentile 33 / cohort 1975
ESI 0.279 · percentile 23 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period
4.400 days
Semi-major axis
0.0497 AU
Eccentricity
Inclination
°

Year Length

A year here lasts approximately 4.40 Earth days (1.2% of a terrestrial year) at a mean orbital distance of 0.0497 AU.

Transit Fingerprint

Depth

0.168 %

Duration

1.560 h

Impact parameter b

0.380

Rp / R★

0.035000

Transit midpoint (BJD)

2,457,142.9751

Photometric dip

Transit produces a flux drop of 1,682 ppm lasting ≈ 1.56 h.

Extended Orbital Architecture

Planet / star radius ratio

0.035000

Semi-major axis / stellar radius

20.940

Impact parameter (b)

0.380

Transit mid-time (BJD)

2,457,142.9751

Angular separation (arcsec)

0.17700

Eq. Temperature

848K

(575 °C)

Insolation (S⊕)

Earth = 1.00

Earth Similarity (ESI)

0.279

0 = alien, 1 = Earth-identical

Insufficient insolation data — the surface is too hot to retain surface water. 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: K2-270

Spectral Class

K-type orange

Effective Temperature

4,877 K — cooler than the Sun (5,778 K)

Estimated Age

Stellar Radius

0.770 R☉

Stellar Mass

0.850 M☉

Metallicity [Fe/H]

0.26

Extended Stellar Properties

Surface gravity (log g)

4.590 dex

Stellar density

1.886 g/cm³

Metallicity ratio

[Fe/H]

Distance
280.52 parsec
Light-years 914.93 ly
V-band magnitude
13.85 mag
Voyager-speed travel 16,134,724 yr

Multi-band Host Photometry — 17 bands

8.716.716.69U14.82B13.85V13.47Gaia13.43Kepler12.83TESS15.13Sloan g13.56Sloan r13.31Sloan i13.41Sloan z11.97J11.46H11.37K11.29W111.38W211.49W38.73W4

Astrometric Data

Parallax

3.536 mas

Total Proper Motion

25.670 mas/yr

PM Right Ascension

-11.82 mas/yr

PM Declination

-22.79 mas/yr

Galactic Cartesian (pc)

x = -0.641 · y = 0.731 · z = 0.234

Equatorial (J2000)

RA 131.26656° · Dec 13.54973°

Galactic ℓ, b

213.091° · 31.228°

Ecliptic λ, β

130.016° · -4.342°

HTM-20 index

-411806528

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