Confirmed Exoplanet Discovered 2018

K2-141 c

A neptune-like orbiting the k-type orange K2-141, located approximately 201.8 light-years from Earth.

Key parameters at a glance

  • A radius of 7.00 Earth radii
  • A mass of 8.00 Earth masses
  • Surface gravity around 0.16 g
  • An orbital period of 7.749 days
  • Semi-major axis 0.0683 AU
  • Equilibrium temperature 695 K (422 °C)
  • Distance from Earth 201.80 light-years
  • Earth Similarity Index 0.150
  • Travel time at Voyager 1 speed 3,558,821 years
  • Almost certainly tidally locked to its host star given the close orbit

1 sibling around K2-141

K2-141 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
K2-141 b Super-Earth 1.51 4.97 0.280 2,103 2018
K2-141 c this Neptune-like 7.00 8.00 7.749 695 2018

K2-141 c Planet Profile

Physical Specs

Radius
7.00 R⊕
Radius (Jupiter)
0.625 R♃
Mass
8.00 M⊕
Mass (Jupiter)
0.025 M♃
Density
0.08 g/cm³
Surface Gravity
0.16 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.150
HZ Position Inner
Controversial No

Discovery

Year 2018
Method Transit
Facility K2
Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#202of 574

top 35.0%

This planet

7.00R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

Metric Earth K2-141 c Jupiter
Radius (R⊕)1.007.0011.21
Mass (M⊕)1.008.00317.83
Density (g/cm³)5.510.081.33
Surface Gravity (g)1.000.162.53
Insolation (S⊕)1.0039.100.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 8.000 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 301235044

Gaia DR2

Gaia DR2 2643952940813536768

Gaia DR3

Gaia DR3 2643952940813536768

System

K2-141

Percentile among Neptune-like cohort

Radius 7.000 R⊕ · percentile 65 / cohort 574
Mass 8.000 M⊕ · percentile 3 / cohort 574
Orbital period 7.75 d · percentile 30 / cohort 524
Distance 61.87 pc · percentile 18 / cohort 572
ESI 0.150 · percentile 14 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period
7.749 days
Semi-major axis
0.0683 AU
Eccentricity
0.092
Inclination
87.20 °

Year Length

A year here lasts approximately 7.75 Earth days (2.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0683 AU.

Transit Fingerprint

Rp / R★

0.094000

Transit midpoint (BJD)

2,457,751.1546

Extended Orbital Architecture

Planet / star radius ratio

0.094000

Semi-major axis / stellar radius

21.590

RV semi-amplitude (K)

3.200 m/s

Transit mid-time (BJD)

2,457,751.1546

Long. of periastron (ω)

90.00°

Angular separation (arcsec)

1.10000

Eq. Temperature

695K

(422 °C)

Insolation (S⊕)

39.10

Earth = 1.00

Earth Similarity (ESI)

0.150

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.

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

Malavolta et al. 2018

Instrument

Kepler CCD Array

Publication

2018-03

Observation locale

Space

Host System: K2-141

Spectral Class

K-type orange

Effective Temperature

4,570 K — cooler than the Sun (5,778 K)

Estimated Age

6.30 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.681 R☉

Stellar Mass

0.708 M☉

Metallicity [Fe/H]

0.00

Extended Stellar Properties

Surface gravity (log g)

4.620 dex

Stellar density

3.860 g/cm³

Systemic radial velocity

-3.62 km/s

Rotational v·sin i

3.00 km/s

Rotation period

15.17 days

Metallicity ratio

[Fe/H]

Distance
61.87 parsec
Light-years 201.80 ly
V-band magnitude
11.45 mag
Voyager-speed travel 3,558,821 yr

Multi-band Host Photometry — 18 bands

7.915.615.63U12.14B11.45V10.72Gaia10.62Kepler10.03TESS11.95Sloan g10.73Sloan r10.37Sloan i10.94Sloan z9.97Ic9.09J8.52H8.40K8.31W18.39W28.31W37.93W4

Astrometric Data

Parallax

16.133 mas

Total Proper Motion

118.904 mas/yr

PM Right Ascension

116.17 mas/yr

PM Declination

25.36 mas/yr

Galactic Cartesian (pc)

x = 0.987 · y = -0.158 · z = -0.021

Equatorial (J2000)

RA 350.91705° · Dec -1.18918°

Galactic ℓ, b

80.199° · -56.595°

Ecliptic λ, β

351.183° · 2.507°

HTM-20 index

851368038

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