Key parameters at a glance

A radius of 2.03 Earth radii
A mass of 4.78 Earth masses
Surface gravity around 1.16 g
An orbital period of 27.860 days
Semi-major axis 0.1768 AU
Distance from Earth 929.14 light-years
Earth Similarity Index 0.780
Travel time at Voyager 1 speed 16,385,386 years

1 sibling around K2-84

K2-84 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
K2-84 b	Sub-Neptune	2.41	6.39	6.422	—	2016
K2-84 c this	Sub-Neptune	2.03	4.78	27.860	—	2016

K2-84 c Planet Profile

Physical Specs

Radius

2.03 R⊕

Radius (Jupiter)

0.181 R♃

Mass

4.78 M⊕

Mass (Jupiter)

0.015 M♃

Density

3.14 g/cm³

Surface Gravity

1.16 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.780

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

#1915of 1978

top 96.8%

This planet

2.03R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

GJ 2030 b 2.03 R⊕ Kepler-37 d 2.03 R⊕ Kepler-195 b 2.03 R⊕

Metric	Earth	K2-84 c	Jupiter
Radius (R⊕)	1.00	2.03	11.21
Mass (M⊕)	1.00	4.78	317.83
Density (g/cm³)	5.51	3.14	1.33
Surface Gravity (g)	1.00	1.16	2.53
Insolation (S⊕)	1.00	25.30	0.037

Star Catalogue Identifiers

TIC

TIC 434133930

Gaia DR2

Gaia DR2 44062348664673152

Gaia DR3

Gaia DR3 44062348664673152

System

K2-84

Percentile among Sub-Neptune cohort

Radius 2.030 R⊕ · percentile 3 / cohort 1978

Mass 4.780 M⊕ · percentile 5 / cohort 1978

Orbital period 27.86 d · percentile 71 / cohort 1946

Distance 284.88 pc · percentile 34 / cohort 1975

ESI 0.780 · percentile 99 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

27.860 days

Semi-major axis

0.1768 AU

Eccentricity

—

Inclination

— °

Year Length

A year here lasts approximately 27.86 Earth days (7.6% of a terrestrial year) at a mean orbital distance of 0.1768 AU.

Transit Fingerprint

Depth

0.070 %

Duration

4.610 h

Rp / R★

0.019800

Transit midpoint (BJD)

2,457,068.6150

Photometric dip

Transit produces a flux drop of 704 ppm lasting ≈ 4.61 h.

Extended Orbital Architecture

Planet / star radius ratio

0.019800

Semi-major axis / stellar radius

42.900

Transit mid-time (BJD)

2,457,068.6150

Angular separation (arcsec)

0.62100

Eq. Temperature

—

Insolation (S⊕)

25.30

Earth = 1.00

Earth Similarity (ESI)

0.780

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Crossfield et al. 2016

Instrument

Kepler CCD Array

Publication

2016-09

Observation locale

Space

Discovery cohort

Planets confirmed in 2016 at K2 (12 shown).

K2-72 d · Rocky Terrestrial K2-72 b · Rocky Terrestrial K2-91 b · Rocky Terrestrial K2-72 c · Rocky Terrestrial K2-102 b · Super-Earth K2-90 c · Super-Earth K2-72 e · Super-Earth K2-83 b · Rocky Terrestrial K2-88 b · Rocky Terrestrial K2-80 c · Super-Earth K2-83 c · Super-Earth K2-65 b · Super-Earth

Host System: K2-84

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,652 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.930 R☉

Stellar Mass

0.950 M☉

Metallicity [Fe/H]

0.28

Extended Stellar Properties

Surface gravity (log g)

4.481 dex

Stellar density

2.291 g/cm³

Systemic radial velocity

7.64 km/s

Metallicity ratio

[M/H]

Distance

284.88 parsec

Light-years 929.14 ly

V-band magnitude

13.39 mag

Voyager-speed travel 16,385,386 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

3.482 mas

Total Proper Motion

33.117 mas/yr

PM Right Ascension

21.51 mas/yr

PM Declination

-25.19 mas/yr

Galactic Cartesian (pc)

x = 0.538 · y = 0.793 · z = 0.286

Equatorial (J2000)

RA 55.80936° · Dec 16.63444°

Galactic ℓ, b

171.581° · -29.580°

Ecliptic λ, β

57.368° · -3.016°

HTM-20 index

1791886602