Confirmed Exoplanet Discovered 2017

K2-131 b

A super-earth orbiting the k-type orange K2-131, located approximately 497.4 light-years from Earth.

Key parameters at a glance

  • A radius of 1.69 Earth radii
  • A mass of 7.90 Earth masses
  • Surface gravity around 2.77 g
  • An orbital period of 0.369 days
  • Semi-major axis 0.0094 AU
  • Equilibrium temperature 2,223 K (1950 °C)
  • Distance from Earth 497.42 light-years
  • Earth Similarity Index 0.106
  • Travel time at Voyager 1 speed 8,771,953 years
  • Almost certainly tidally locked to its host star given the close orbit

K2-131 b Planet Profile

Physical Specs

Radius
1.69 R⊕
Radius (Jupiter)
0.151 R♃
Mass
7.90 M⊕
Mass (Jupiter)
0.025 M♃
Density
8.80 g/cm³
Surface Gravity
2.77 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.106
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

#415of 1176

top 35.2%

This planet

1.69R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Metric Earth K2-131 b Jupiter
Radius (R⊕)1.001.6911.21
Mass (M⊕)1.007.90317.83
Density (g/cm³)5.518.801.33
Surface Gravity (g)1.002.772.53
Insolation (S⊕)1.004,070.000.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 7.900 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 176868951

Gaia DR2

Gaia DR2 3580920878437938688

Gaia DR3

Gaia DR3 3580920878437938688

System

K2-131

Percentile among Super-Earth cohort

Radius 1.690 R⊕ · percentile 64 / cohort 1176
Mass 7.900 M⊕ · percentile 95 / cohort 1176
Orbital period 0.37 d · percentile 0 / cohort 1164
Distance 152.51 pc · percentile 20 / cohort 1171
ESI 0.106 · percentile 1 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period
0.369 days
Semi-major axis
0.0094 AU
Eccentricity
0.000
Inclination
85.00 °

Year Length

A year here lasts roughly 8.9 hours long on a nearly circular orbit at a mean orbital distance of 0.0094 AU.

Transit Fingerprint

Depth

0.076 %

Duration

1.003 h

Impact parameter b

0.400

Rp / R★

0.017200

Transit midpoint (BJD)

2,457,582.9360

Photometric dip

Transit produces a flux drop of 756 ppm lasting ≈ 1.00 h.

Extended Orbital Architecture

Planet / star radius ratio

0.017200

Semi-major axis / stellar radius

3.000

Impact parameter (b)

0.400

RV semi-amplitude (K)

8.000 m/s

Transit mid-time (BJD)

2,457,582.9360

Angular separation (arcsec)

0.06140

Eq. Temperature

2,223K

(1950 °C)

Insolation (S⊕)

4,070.00

Earth = 1.00

Earth Similarity (ESI)

0.106

0 = alien, 1 = Earth-identical

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

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Discovery Paper

Primary reference

Dai et al. 2017

Instrument

Kepler CCD Array

Publication

2017-12

Observation locale

Space

Host System: K2-131

Spectral Class

K-type orange

Effective Temperature

5,120 K — cooler than the Sun (5,778 K)

Estimated Age

5.30 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.760 R☉

Stellar Mass

0.803 M☉

Metallicity [Fe/H]

-0.04

Extended Stellar Properties

Surface gravity (log g)

4.610 dex

Stellar density

2.710 g/cm³

Systemic radial velocity

-5.27 km/s

Rotational v·sin i

4.30 km/s

Rotation period

9.19 days

Metallicity ratio

[Fe/H]

Distance
152.51 parsec
Light-years 497.42 ly
V-band magnitude
12.13 mag
Voyager-speed travel 8,771,953 yr

Multi-band Host Photometry — 12 bands

8.713.113.05B12.13V11.90Gaia11.94Kepler11.33TESS10.57J10.12H10.05K9.95W110.00W29.91W38.67W4

Astrometric Data

Parallax

6.529 mas

Total Proper Motion

39.849 mas/yr

PM Right Ascension

-39.49 mas/yr

PM Declination

-5.37 mas/yr

Galactic Cartesian (pc)

x = -0.984 · y = -0.047 · z = -0.170

Equatorial (J2000)

RA 182.75140° · Dec -9.76524°

Galactic ℓ, b

286.681° · 51.826°

Ecliptic λ, β

186.422° · -7.863°

HTM-20 index

683999477

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