Confirmed Exoplanet Discovered 2016

K2-68 b

A super-earth orbiting the k-type orange K2-68, located approximately 550.1 light-years from Earth.

Key parameters at a glance

  • A radius of 1.58 Earth radii
  • A mass of 3.12 Earth masses
  • Surface gravity around 1.25 g
  • An orbital period of 8.054 days
  • Semi-major axis 0.0708 AU
  • Distance from Earth 550.07 light-years
  • Earth Similarity Index 0.873
  • Travel time at Voyager 1 speed 9,700,460 years
  • Almost certainly tidally locked to its host star given the close orbit

K2-68 b Planet Profile

Physical Specs

Radius
1.58 R⊕
Radius (Jupiter)
0.141 R♃
Mass
3.12 M⊕
Mass (Jupiter)
0.010 M♃
Density
4.35 g/cm³
Surface Gravity
1.25 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.873
HZ Position Inner
Controversial No

Discovery

Year 2016
Method Transit
Facility K2
Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#603of 1176

top 51.2%

This planet

1.58R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Metric Earth K2-68 b Jupiter
Radius (R⊕)1.001.5811.21
Mass (M⊕)1.003.12317.83
Density (g/cm³)5.514.351.33
Surface Gravity (g)1.001.252.53
Insolation (S⊕)1.0041.000.037

Star Catalogue Identifiers

TIC

TIC 38258419

Gaia DR2

Gaia DR2 2614734243939231232

Gaia DR3

Gaia DR3 2614734243939231232

System

K2-68

Percentile among Super-Earth cohort

Radius 1.580 R⊕ · percentile 48 / cohort 1176
Mass 3.120 M⊕ · percentile 44 / cohort 1176
Orbital period 8.05 d · percentile 57 / cohort 1164
Distance 168.65 pc · percentile 22 / cohort 1171
ESI 0.873 · percentile 95 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period
8.054 days
Semi-major axis
0.0708 AU
Eccentricity
Inclination
88.72 °

Year Length

A year here lasts approximately 8.05 Earth days (2.2% of a terrestrial year) at a mean orbital distance of 0.0708 AU.

Transit Fingerprint

Depth

0.067 %

Duration

2.720 h

Impact parameter b

0.090

Rp / R★

0.021100

Transit midpoint (BJD)

2,456,982.3281

Photometric dip

Transit produces a flux drop of 668 ppm lasting ≈ 2.72 h.

Extended Orbital Architecture

Planet / star radius ratio

0.021100

Semi-major axis / stellar radius

19.902

Impact parameter (b)

0.090

Transit mid-time (BJD)

2,456,982.3281

Angular separation (arcsec)

0.42000

Eq. Temperature

 

Insolation (S⊕)

41.00

Earth = 1.00

Earth Similarity (ESI)

0.873

0 = alien, 1 = Earth-identical

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

Discovery Paper

Primary reference

Crossfield et al. 2016

Instrument

Kepler CCD Array

Publication

2016-09

Observation locale

Space

Host System: K2-68

Spectral Class

K-type orange

Effective Temperature

4,746 K — cooler than the Sun (5,778 K)

Estimated Age

Stellar Radius

0.675 R☉

Stellar Mass

0.730 M☉

Metallicity [Fe/H]

-0.21

Extended Stellar Properties

Surface gravity (log g)

4.632 dex

Stellar density

3.285 g/cm³

Systemic radial velocity

18.73 km/s

Metallicity ratio

[Fe/H]

Distance
168.65 parsec
Light-years 550.07 ly
V-band magnitude
12.99 mag
Voyager-speed travel 9,700,460 yr

Multi-band Host Photometry — 12 bands

8.614.013.98B12.99V12.66Gaia12.60Kepler12.03TESS11.14J10.65H10.53K10.46W110.52W210.52W38.56W4

Astrometric Data

Parallax

5.901 mas

Total Proper Motion

53.375 mas/yr

PM Right Ascension

-52.53 mas/yr

PM Declination

-9.49 mas/yr

Galactic Cartesian (pc)

x = 0.884 · y = -0.431 · z = -0.183

Equatorial (J2000)

RA 334.01955° · Dec -10.56736°

Galactic ℓ, b

49.714° · -49.914°

Ecliptic λ, β

332.088° · 0.174°

HTM-20 index

411061059

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