Confirmed Exoplanet Discovered 2018

K2-285 e

A super-earth orbiting the k-type orange K2-285, located approximately 505.4 light-years from Earth.

Key parameters at a glance

  • A radius of 1.95 Earth radii
  • A mass of 10.70 Earth masses
  • Surface gravity around 2.81 g
  • An orbital period of 14.763 days
  • Semi-major axis 0.1804 AU
  • Equilibrium temperature 501 K (228 °C)
  • Distance from Earth 505.41 light-years
  • Earth Similarity Index 0.459
  • Travel time at Voyager 1 speed 8,912,986 years
  • Almost certainly tidally locked to its host star given the close orbit

3 siblings around K2-285

K2-285 e shares its host star with 3 other confirmed planets. Side-by-side measurements below.

Planet Type Radius (R⊕) Mass (M⊕) Period (d) Eq. T (K) Year
K2-285 b Sub-Neptune 2.59 9.68 3.472 1,089 2018
K2-285 c Sub-Neptune 3.53 15.68 7.138 741 2018
K2-285 d Sub-Neptune 2.48 6.50 10.456 620 2018
K2-285 e this Super-Earth 1.95 10.70 14.763 501 2018

K2-285 e Planet Profile

Physical Specs

Radius
1.95 R⊕
Radius (Jupiter)
0.174 R♃
Mass
10.70 M⊕
Mass (Jupiter)
0.034 M♃
Density
g/cm³
Surface Gravity
2.81 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.459
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

#67of 1176

top 5.6%

This planet

1.95R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Metric Earth K2-285 e Jupiter
Radius (R⊕)1.001.9511.21
Mass (M⊕)1.0010.70317.83
Density (g/cm³)5.511.33
Surface Gravity (g)1.002.812.53
Insolation (S⊕)1.0010.500.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 10.700 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 262715204

Gaia DR2

Gaia DR2 2657374606238804992

Gaia DR3

Gaia DR3 2657374606238804992

System

K2-285

Percentile among Super-Earth cohort

Radius 1.950 R⊕ · percentile 94 / cohort 1176
Mass 10.700 M⊕ · percentile 97 / cohort 1176
Orbital period 14.76 d · percentile 77 / cohort 1164
Distance 154.96 pc · percentile 20 / cohort 1171
ESI 0.459 · percentile 69 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period
14.763 days
Semi-major axis
0.1804 AU
Eccentricity
0.000
Inclination
89.80 °

Year Length

A year here lasts approximately 14.76 Earth days (4.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1804 AU.

Transit Fingerprint

Depth

0.068 %

Duration

2.300 h

Impact parameter b

0.170

Rp / R★

0.022704

Transit midpoint (BJD)

2,457,741.8969

Photometric dip

Transit produces a flux drop of 680 ppm lasting ≈ 2.30 h.

Extended Orbital Architecture

Planet / star radius ratio

0.022704

Semi-major axis / stellar radius

49.430

Impact parameter (b)

0.170

RV semi-amplitude (K)

1.690 m/s

Transit mid-time (BJD)

2,457,741.8969

Angular separation (arcsec)

1.16000

Eq. Temperature

501K

(228 °C)

Insolation (S⊕)

10.50

Earth = 1.00

Earth Similarity (ESI)

0.459

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.

Discovery Paper

Primary reference

Palle et al. 2019

Instrument

Kepler CCD Array

Publication

2019-03

Observation locale

Space

Host System: K2-285

Spectral Class

K-type orange

Effective Temperature

4,975 K — cooler than the Sun (5,778 K)

Estimated Age

Stellar Radius

0.787 R☉

Stellar Mass

0.830 M☉

Metallicity [Fe/H]

0.00

Extended Stellar Properties

Surface gravity (log g)

4.400 dex

Stellar density

2.512 g/cm³

Systemic radial velocity

15.88 km/s

Rotational v·sin i

3.90 km/s

Metallicity ratio

[Fe/H]

Distance
154.96 parsec
Light-years 505.41 ly
V-band magnitude
12.08 mag
Voyager-speed travel 8,912,986 yr

Multi-band Host Photometry — 17 bands

8.715.515.52U12.92B12.08V11.80Gaia11.67Kepler11.25TESS12.75Sloan g11.84Sloan r11.58Sloan i11.92Sloan z10.48J10.07H9.97K9.89W19.97W29.90W38.74W4

Astrometric Data

Parallax

6.425 mas

Total Proper Motion

37.056 mas/yr

PM Right Ascension

15.02 mas/yr

PM Declination

-33.87 mas/yr

Galactic Cartesian (pc)

x = 0.983 · y = -0.184 · z = 0.023

Equatorial (J2000)

RA 349.38435° · Dec 1.30015°

Galactic ℓ, b

80.675° · -53.685°

Ecliptic λ, β

350.751° · 5.398°

HTM-20 index

204873357

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