Key parameters at a glance

A radius of 2.23 Earth radii
A mass of 40.00 Earth masses
Surface gravity around 8.04 g
An orbital period of 8.726 days
Semi-major axis 0.0827 AU
Equilibrium temperature 985 K (712 °C)
Distance from Earth 3,339.51 light-years
Earth Similarity Index 0.209
Travel time at Voyager 1 speed 58,892,278 years

4 siblings around Kepler-84

Kepler-84 b shares its host star with 4 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-84 d	Super-Earth	1.38	2.48	4.225	1,254	2014
Kepler-84 b this	Sub-Neptune	2.23	40.00	8.726	985	2012
Kepler-84 c	Sub-Neptune	2.36	20.20	12.883	865	2012
Kepler-84 e	Sub-Neptune	2.60	7.27	27.434	672	2014
Kepler-84 f	Sub-Neptune	2.20	5.48	44.552	572	2014

Kepler-84 b Planet Profile

Physical Specs

Radius

2.23 R⊕

Radius (Jupiter)

0.199 R♃

Mass

40.00 M⊕

Mass (Jupiter)

0.126 M♃

Density

19.80 g/cm³

Surface Gravity

8.04 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.209

HZ Position Inner

Controversial No

Discovery

Year 2012

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#1622of 1978

top 82.0%

This planet

2.23R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-292 d 2.23 R⊕ Kepler-165 c 2.23 R⊕ Kepler-235 b 2.23 R⊕

Metric	Earth	Kepler-84 b	Jupiter
Radius (R⊕)	1.00	2.23	11.21
Mass (M⊕)	1.00	40.00	317.83
Density (g/cm³)	5.51	19.80	1.33
Surface Gravity (g)	1.00	8.04	2.53
Insolation (S⊕)	1.00	222.19	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	40.000 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 170646917

Gaia DR2

Gaia DR2 2073776859551124992

Gaia DR3

Gaia DR3 2073776859551124992

System

Kepler-84

Percentile among Sub-Neptune cohort

Radius 2.230 R⊕ · percentile 17 / cohort 1978

Mass 40.000 M⊕ · percentile 97 / cohort 1978

Orbital period 8.73 d · percentile 29 / cohort 1946

Distance 1,023.90 pc · percentile 79 / cohort 1975

ESI 0.209 · percentile 8 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

8.726 days

Semi-major axis

0.0827 AU

Eccentricity

0.000

Inclination

82.52 °

Year Length

A year here lasts approximately 8.73 Earth days (2.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0827 AU.

Transit Fingerprint

Depth

0.045 %

Duration

4.473 h

Impact parameter b

0.420

Rp / R★

0.019710

Transit midpoint (BJD)

2,454,971.7541

Photometric dip

Transit produces a flux drop of 447 ppm lasting ≈ 4.47 h.

Extended Orbital Architecture

Planet / star radius ratio

0.019710

Semi-major axis / stellar radius

5.930

Impact parameter (b)

0.420

Transit mid-time (BJD)

2,454,971.7541

Angular separation (arcsec)

0.08080

Eq. Temperature

985K

(712 °C)

Insolation (S⊕)

222.19

Earth = 1.00

Earth Similarity (ESI)

0.209

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Xie 2013

Instrument

Kepler CCD Array

Publication

2013-10

Observation locale

Space

Discovery cohort

Planets confirmed in 2012 at Kepler (12 shown).

Kepler-54 c · Rocky Terrestrial Kepler-49 c · Sub-Neptune Kepler-55 b · Sub-Neptune Kepler-49 b · Sub-Neptune Kepler-81 c · Sub-Neptune Kepler-55 c · Sub-Neptune Kepler-52 c · Super-Earth Kepler-83 c · Sub-Neptune Kepler-32 d · Sub-Neptune Kepler-83 b · Sub-Neptune Kepler-54 b · Sub-Neptune Kepler-80 c · Sub-Neptune

Host System: Kepler-84

Spectral Class

F-type yellow-white

Effective Temperature

6,039 K — hotter than the Sun (5,778 K)

Estimated Age

3.98 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.430 R☉

Stellar Mass

1.000 M☉

Metallicity [Fe/H]

-0.07

Extended Stellar Properties

Surface gravity (log g)

4.130 dex

Stellar density

0.029 g/cm³

Metallicity ratio

[Fe/H]

Distance

1,023.90 parsec

Light-years 3,339.51 ly

V-band magnitude

14.92 mag

Voyager-speed travel 58,892,278 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.693 mas

Total Proper Motion

4.035 mas/yr

PM Right Ascension

-1.08 mas/yr

PM Declination

-3.89 mas/yr

Galactic Cartesian (pc)

x = 0.360 · y = -0.670 · z = 0.649

Equatorial (J2000)

RA 298.25202° · Dec 40.49608°

Galactic ℓ, b

75.354° · 6.689°

Ecliptic λ, β

315.291° · 59.572°

HTM-20 index

-620986613