Key parameters at a glance

A radius of 1.46 Earth radii
A mass of 2.20 Earth masses
Surface gravity around 1.03 g
An orbital period of 44.556 days
Semi-major axis 0.2014 AU
Equilibrium temperature 305 K (32 °C)
Distance from Earth 143.75 light-years
Earth Similarity Index 0.751
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

K2-3d, also known as EPIC 201367065 d, is a confirmed exoplanet of probable mini-Neptune type orbiting the red dwarf star K2-3, and the outermost of three such planets discovered in the system. It is located 143 light-years away from Earth in the constellation of Leo. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. It was the first planet in the Kepler "Second Light" mission to receive the letter "d" designation for a planet. Its discovery was announced in January 2015.

Excerpted from Wikipedia · full article

2 siblings around K2-3

K2-3 d 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	Super-Earth	1.58	2.68	24.647	372	2015
K2-3 d this	Super-Earth	1.46	2.20	44.556	305	2015

K2-3 d Planet Profile

Physical Specs

Radius

1.46 R⊕

Radius (Jupiter)

0.130 R♃

Mass

2.20 M⊕

Mass (Jupiter)

0.007 M♃

Density

17.50 g/cm³

Surface Gravity

1.03 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.751

HZ Position Habitable

Controversial No

Discovery

Year 2015

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#836of 1176

top 71.0%

This planet

1.46R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-1834 b 1.46 R⊕ Kepler-366 b 1.46 R⊕ Kepler-190 c 1.46 R⊕

Metric	Earth	K2-3 d	Jupiter
Radius (R⊕)	1.00	1.46	11.21
Mass (M⊕)	1.00	2.20	317.83
Density (g/cm³)	5.51	17.50	1.33
Surface Gravity (g)	1.00	1.03	2.53
Insolation (S⊕)	1.00	1.44	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	2.200 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 1.458 R⊕ · percentile 29 / cohort 1176

Mass 2.200 M⊕ · percentile 6 / cohort 1176

Orbital period 44.56 d · percentile 95 / cohort 1164

Distance 44.07 pc · percentile 9 / cohort 1171

ESI 0.751 · percentile 87 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

44.556 days

Semi-major axis

0.2014 AU

Eccentricity

0.091

Inclination

89.82 °

Year Length

A year here lasts approximately 44.56 Earth days (12.2% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2014 AU.

Transit Fingerprint

Depth

0.078 %

Duration

4.170 h

Impact parameter b

0.240

Rp / R★

0.024490

Transit midpoint (BJD)

2,457,271.7880

Photometric dip

Transit produces a flux drop of 782 ppm lasting ≈ 4.17 h.

Extended Orbital Architecture

Planet / star radius ratio

0.024490

Semi-major axis / stellar radius

79.400

Impact parameter (b)

0.240

RV semi-amplitude (K)

1.910 m/s

Transit mid-time (BJD)

2,457,271.7880

Long. of periastron (ω)

0.00°

Angular separation (arcsec)

4.57000

Eq. Temperature

305K

(32 °C)

Insolation (S⊕)

1.44

Earth = 1.00

Earth Similarity (ESI)

0.751

0 = alien, 1 = Earth-identical

Within the conservative habitable zone — 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 c · 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

Wikipedia → Image: Wikimedia Commons · MarioProtIV · CC BY-SA 4.0