Confirmed Exoplanet Discovered 2018

K2-252 b

A super-earth orbiting the k-type orange K2-252, located approximately 746.4 light-years from Earth.

Key parameters at a glance

  • A radius of 1.74 Earth radii
  • A mass of 3.68 Earth masses
  • Surface gravity around 1.22 g
  • An orbital period of 13.815 days
  • Semi-major axis 0.1041 AU
  • Equilibrium temperature 639 K (366 °C)
  • Distance from Earth 746.37 light-years
  • Earth Similarity Index 0.451
  • Travel time at Voyager 1 speed 13,162,272 years
  • Almost certainly tidally locked to its host star given the close orbit

K2-252 b Planet Profile

Physical Specs

Radius
1.74 R⊕
Radius (Jupiter)
0.155 R♃
Mass
3.68 M⊕
Mass (Jupiter)
0.012 M♃
Density
3.84 g/cm³
Surface Gravity
1.22 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.451
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

#344of 1176

top 29.2%

This planet

1.74R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Metric Earth K2-252 b Jupiter
Radius (R⊕)1.001.7411.21
Mass (M⊕)1.003.68317.83
Density (g/cm³)5.513.841.33
Surface Gravity (g)1.001.222.53
Insolation (S⊕)1.000.037

Star Catalogue Identifiers

TIC

TIC 152868838

Gaia DR2

Gaia DR2 3582392123779246336

Gaia DR3

Gaia DR3 3582392123779246336

System

K2-252

Percentile among Super-Earth cohort

Radius 1.740 R⊕ · percentile 70 / cohort 1176
Mass 3.680 M⊕ · percentile 64 / cohort 1176
Orbital period 13.82 d · percentile 75 / cohort 1164
Distance 228.84 pc · percentile 26 / cohort 1171
ESI 0.451 · percentile 68 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period
13.815 days
Semi-major axis
0.1041 AU
Eccentricity
Inclination
°

Year Length

A year here lasts approximately 13.82 Earth days (3.8% of a terrestrial year) at a mean orbital distance of 0.1041 AU.

Transit Fingerprint

Depth

0.036 %

Duration

3.600 h

Impact parameter b

0.410

Rp / R★

0.019300

Transit midpoint (BJD)

2,457,596.1901

Photometric dip

Transit produces a flux drop of 360 ppm lasting ≈ 3.60 h.

Extended Orbital Architecture

Planet / star radius ratio

0.019300

Semi-major axis / stellar radius

25.700

Impact parameter (b)

0.410

Transit mid-time (BJD)

2,457,596.1901

Angular separation (arcsec)

0.45500

Eq. Temperature

639K

(366 °C)

Insolation (S⊕)

Earth = 1.00

Earth Similarity (ESI)

0.451

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

2018-08

Observation locale

Space

Host System: K2-252

Spectral Class

K-type orange

Effective Temperature

5,152 K — cooler than the Sun (5,778 K)

Estimated Age

Stellar Radius

0.820 R☉

Stellar Mass

0.790 M☉

Metallicity [Fe/H]

-0.09

Extended Stellar Properties

Surface gravity (log g)

4.500 dex

Stellar density

2.040 g/cm³

Systemic radial velocity

13.72 km/s

Rotational v·sin i

2.20 km/s

Metallicity ratio

[Fe/H]

Distance
228.84 parsec
Light-years 746.37 ly
V-band magnitude
12.93 mag
Voyager-speed travel 13,162,272 yr

Multi-band Host Photometry — 12 bands

8.813.813.80B12.93V12.62Gaia12.64Kepler12.05TESS11.24J10.77H10.68K10.66W110.72W210.76W38.77W4

Astrometric Data

Parallax

4.341 mas

Total Proper Motion

22.917 mas/yr

PM Right Ascension

3.30 mas/yr

PM Declination

-22.68 mas/yr

Galactic Cartesian (pc)

x = -0.989 · y = -0.041 · z = -0.145

Equatorial (J2000)

RA 182.36638° · Dec -8.30961°

Galactic ℓ, b

285.453° · 53.132°

Ecliptic λ, β

185.483° · -6.681°

HTM-20 index

-488879535

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