Key parameters at a glance

A radius of 1.58 Earth radii
A mass of 2.68 Earth masses
Surface gravity around 1.07 g
An orbital period of 24.647 days
Semi-major axis 0.1357 AU
Equilibrium temperature 372 K (99 °C)
Distance from Earth 143.75 light-years
Earth Similarity Index 0.734
Travel time at Voyager 1 speed 2,534,956 years
Almost certainly tidally locked to its host star given the close orbit

Context from the literature

K2-3c, also known as EPIC 201367065 c, is an exoplanet orbiting the red dwarf star K2-3 every 24 days. It is 143 light-years away. It has a density of about 3.7 g/cm3, indicating that it could be an ocean world or a mini-Neptune. It is the second-smallest planet in the system by both radius and mass, with a mass almost three times that of Earth.

Excerpted from Wikipedia · full article

2 siblings around K2-3

K2-3 c shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
K2-3 b	Sub-Neptune	2.08	5.11	10.055	501	2015
K2-3 c this	Super-Earth	1.58	2.68	24.647	372	2015
K2-3 d	Super-Earth	1.46	2.20	44.556	305	2015

K2-3 c Planet Profile

Physical Specs

Radius

1.58 R⊕

Radius (Jupiter)

0.141 R♃

Mass

2.68 M⊕

Mass (Jupiter)

0.008 M♃

Density

3.70 g/cm³

Surface Gravity

1.07 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.734

HZ Position Inner

Controversial No

Discovery

Year 2015

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#602of 1176

top 51.1%

This planet

1.58R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-1859 b 1.58 R⊕ Kepler-445 b 1.58 R⊕ Kepler-386 c 1.58 R⊕

Metric	Earth	K2-3 c	Jupiter
Radius (R⊕)	1.00	1.58	11.21
Mass (M⊕)	1.00	2.68	317.83
Density (g/cm³)	5.51	3.70	1.33
Surface Gravity (g)	1.00	1.07	2.53
Insolation (S⊕)	1.00	3.17	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	2.680 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 173103335

Gaia DR2

Gaia DR2 3796690380302214272

Gaia DR3

Gaia DR3 3796690380302214272

System

K2-3

Percentile among Super-Earth cohort

Radius 1.582 R⊕ · percentile 49 / cohort 1176

Mass 2.680 M⊕ · percentile 26 / cohort 1176

Orbital period 24.65 d · percentile 88 / cohort 1164

Distance 44.07 pc · percentile 9 / cohort 1171

ESI 0.734 · percentile 86 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

24.647 days

Semi-major axis

0.1357 AU

Eccentricity

0.048

Inclination

89.84 °

Year Length

A year here lasts approximately 24.65 Earth days (6.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1357 AU.

Transit Fingerprint

Depth

0.082 %

Duration

3.428 h

Impact parameter b

0.140

Rp / R★

0.026580

Transit midpoint (BJD)

2,457,329.8569

Photometric dip

Transit produces a flux drop of 822 ppm lasting ≈ 3.43 h.

Extended Orbital Architecture

Planet / star radius ratio

0.026580

Semi-major axis / stellar radius

53.500

Impact parameter (b)

0.140

RV semi-amplitude (K)

0.880 m/s

Transit mid-time (BJD)

2,457,329.8569

Long. of periastron (ω)

-180.00°

Angular separation (arcsec)

3.08000

Eq. Temperature

372K

(99 °C)

Insolation (S⊕)

3.17

Earth = 1.00

Earth Similarity (ESI)

0.734

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — liquid water is physically possible with adequate atmospheric pressure. 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

Crossfield et al. 2015

Instrument

Kepler CCD Array

Publication

2015-05

Observation locale

Space

Discovery cohort

Planets confirmed in 2015 at K2 (12 shown).

K2-18 b · Sub-Neptune K2-9 b · Sub-Neptune K2-3 d · Super-Earth K2-21 c · Sub-Neptune K2-5 c · Sub-Neptune K2-13 b · Super-Earth K2-3 b · Sub-Neptune K2-17 b · Sub-Neptune K2-21 b · Super-Earth K2-16 c · Sub-Neptune K2-5 b · Super-Earth K2-25 b · Sub-Neptune

Host System: K2-3

Spectral Class

M-type red dwarf

Effective Temperature

3,844 K — cooler than the Sun (5,778 K)

Estimated Age

6.90 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.546 R☉

Stellar Mass

0.549 M☉

Metallicity [Fe/H]

-0.16

Extended Stellar Properties

Surface gravity (log g)

4.704 dex

Stellar density

4.780 g/cm³

Systemic radial velocity

30.48 km/s

Rotation period

40.71 days

Metallicity ratio

[Fe/H]

Distance

44.07 parsec

Light-years 143.75 ly

V-band magnitude

12.17 mag

Voyager-speed travel 2,534,956 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

22.661 mas

Total Proper Motion

122.262 mas/yr

PM Right Ascension

94.03 mas/yr

PM Declination

-78.14 mas/yr

Galactic Cartesian (pc)

x = -0.991 · y = 0.133 · z = -0.025

Equatorial (J2000)

RA 172.33537° · Dec -1.45514°

Galactic ℓ, b

264.988° · 55.250°

Ecliptic λ, β

173.533° · -4.378°

HTM-20 index

-116781740

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