Confirmed Exoplanet Discovered 2018

K2-211 b

A super-earth orbiting the k-type orange K2-211, located approximately 888.1 light-years from Earth.

Key parameters at a glance

  • A radius of 1.33 Earth radii
  • A mass of 2.33 Earth masses
  • Surface gravity around 1.31 g
  • An orbital period of 0.670 days
  • Semi-major axis 0.0142 AU
  • Equilibrium temperature 1,873 K (1600 °C)
  • Distance from Earth 888.11 light-years
  • Earth Similarity Index 0.150
  • Travel time at Voyager 1 speed 15,661,872 years
  • Almost certainly tidally locked to its host star given the close orbit

K2-211 b Planet Profile

Physical Specs

Radius
1.33 R⊕
Radius (Jupiter)
0.119 R♃
Mass
2.33 M⊕
Mass (Jupiter)
0.007 M♃
Density
5.42 g/cm³
Surface Gravity
1.31 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.150
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

#1020of 1176

top 86.6%

This planet

1.33R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Metric Earth K2-211 b Jupiter
Radius (R⊕)1.001.3311.21
Mass (M⊕)1.002.33317.83
Density (g/cm³)5.515.421.33
Surface Gravity (g)1.001.312.53
Insolation (S⊕)1.000.037

Star Catalogue Identifiers

TIC

TIC 399731211

Gaia DR2

Gaia DR2 2559203924574351616

Gaia DR3

Gaia DR3 2559203924574351616

System

K2-211

Percentile among Super-Earth cohort

Radius 1.332 R⊕ · percentile 13 / cohort 1176
Mass 2.330 M⊕ · percentile 11 / cohort 1176
Orbital period 0.67 d · percentile 2 / cohort 1164
Distance 272.30 pc · percentile 30 / cohort 1171
ESI 0.150 · percentile 4 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period
0.670 days
Semi-major axis
0.0142 AU
Eccentricity
0.190
Inclination
84.10 °

Year Length

A year here lasts roughly 16.1 hours long on a mildly elliptical path at a mean orbital distance of 0.0142 AU.

Transit Fingerprint

Depth

0.022 %

Duration

1.291 h

Impact parameter b

0.360

Rp / R★

0.014890

Transit midpoint (BJD)

2,457,432.6479

Photometric dip

Transit produces a flux drop of 222 ppm lasting ≈ 1.29 h.

Extended Orbital Architecture

Planet / star radius ratio

0.014890

Semi-major axis / stellar radius

3.730

Impact parameter (b)

0.360

Transit mid-time (BJD)

2,457,432.6479

Long. of periastron (ω)

-150.00°

Angular separation (arcsec)

0.05210

Eq. Temperature

1,873K

(1600 °C)

Insolation (S⊕)

Earth = 1.00

Earth Similarity (ESI)

0.150

0 = alien, 1 = Earth-identical

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

Discovery Paper

Primary reference

Mayo et al. 2018

Instrument

Kepler CCD Array

Publication

2018-03

Observation locale

Space

Host System: K2-211

Spectral Class

K-type orange

Effective Temperature

5,117 K — cooler than the Sun (5,778 K)

Estimated Age

6.50 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.818 R☉

Stellar Mass

0.851 M☉

Metallicity [Fe/H]

0.13

Extended Stellar Properties

Surface gravity (log g)

4.543 dex

Stellar density

2.190 g/cm³

Systemic radial velocity

-13.57 km/s

Metallicity ratio

[Fe/H]

Distance
272.30 parsec
Light-years 888.11 ly
V-band magnitude
13.15 mag
Voyager-speed travel 15,661,872 yr

Multi-band Host Photometry — 17 bands

9.115.815.80U14.03B13.15V12.93Gaia12.87Kepler12.38TESS15.70Sloan g15.30Sloan r15.18Sloan i13.34Sloan z11.62J11.21H11.10K11.07W111.13W210.93W39.09W4

Astrometric Data

Parallax

3.644 mas

Total Proper Motion

49.700 mas/yr

PM Right Ascension

48.66 mas/yr

PM Declination

-10.14 mas/yr

Galactic Cartesian (pc)

x = 0.933 · y = 0.360 · z = 0.030

Equatorial (J2000)

RA 21.10616° · Dec 1.70491°

Galactic ℓ, b

139.643° · -60.092°

Ecliptic λ, β

20.141° · -6.654°

HTM-20 index

620015873

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