Key parameters at a glance

A radius of 1.20 Earth radii
A mass of 1.87 Earth masses
Surface gravity around 1.30 g
An orbital period of 1.499 days
Semi-major axis 0.0232 AU
Equilibrium temperature 1,137 K (864 °C)
Distance from Earth 1,417.75 light-years
Earth Similarity Index 0.270
Travel time at Voyager 1 speed 25,001,984 years
Almost certainly tidally locked to its host star given the close orbit

3 siblings around Kepler-304

Kepler-304 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
Kepler-304 e this	Rocky Terrestrial	1.20	1.87	1.499	1,137	2016
Kepler-304 b	Sub-Neptune	2.86	8.55	3.296	875	2014
Kepler-304 c	Sub-Neptune	2.17	5.35	5.316	746	2014
Kepler-304 d	Sub-Neptune	2.75	8.00	9.653	611	2014

Kepler-304 e Planet Profile

Physical Specs

Radius

1.20 R⊕

Radius (Jupiter)

0.107 R♃

Mass

1.87 M⊕

Mass (Jupiter)

0.006 M♃

Density

5.95 g/cm³

Surface Gravity

1.30 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.270

HZ Position Inner

Controversial No

Discovery

Year 2016

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#75of 570

top 13.0%

This planet

1.20R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-225 b 1.20 R⊕ Kepler-282 c 1.20 R⊕ Kepler-367 c 1.20 R⊕

Metric	Earth	Kepler-304 e	Jupiter
Radius (R⊕)	1.00	1.20	11.21
Mass (M⊕)	1.00	1.87	317.83
Density (g/cm³)	5.51	5.95	1.33
Surface Gravity (g)	1.00	1.30	2.53
Insolation (S⊕)	1.00	397.25	0.037

Star Catalogue Identifiers

TIC

TIC 377909730

Gaia DR2

Gaia DR2 2076565805151925760

Gaia DR3

Gaia DR3 2076565805151925760

System

Kepler-304

Percentile among Rocky Terrestrial cohort

Radius 1.200 R⊕ · percentile 84 / cohort 570

Mass 1.870 M⊕ · percentile 77 / cohort 570

Orbital period 1.50 d · percentile 17 / cohort 567

Distance 434.68 pc · percentile 57 / cohort 566

ESI 0.270 · percentile 29 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

1.499 days

Semi-major axis

0.0232 AU

Eccentricity

0.000

Inclination

87.54 °

Year Length

A year here lasts approximately 1.50 Earth days (0.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0232 AU.

Transit Fingerprint

Depth

0.028 %

Duration

1.442 h

Impact parameter b

0.062

Rp / R★

0.014669

Transit midpoint (BJD)

2,454,966.0686

Photometric dip

Transit produces a flux drop of 276 ppm lasting ≈ 1.44 h.

Extended Orbital Architecture

Planet / star radius ratio

0.014669

Semi-major axis / stellar radius

8.065

Impact parameter (b)

0.062

Transit mid-time (BJD)

2,454,966.0686

Angular separation (arcsec)

0.05330

Eq. Temperature

1,137K

(864 °C)

Insolation (S⊕)

397.25

Earth = 1.00

Earth Similarity (ESI)

0.270

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Morton et al. 2016

Instrument

Kepler CCD Array

Publication

2016-05

Observation locale

Space

Discovery cohort

Planets confirmed in 2016 at Kepler (12 shown).

Kepler-1512 b · Rocky Terrestrial Kepler-1410 b · Super-Earth Kepler-560 b · Super-Earth Kepler-1389 b · Super-Earth Kepler-1450 b · Super-Earth Kepler-1544 b · Super-Earth Kepler-1459 b · Super-Earth Kepler-1638 b · Super-Earth Kepler-737 b · Super-Earth Kepler-1185 b · Super-Earth Kepler-1178 b · Rocky Terrestrial Kepler-1040 b · Sub-Neptune

Host System: Kepler-304

Spectral Class

K-type orange

Effective Temperature

4,817 K — cooler than the Sun (5,778 K)

Estimated Age

2.09 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.730 R☉

Stellar Mass

0.800 M☉

Metallicity [Fe/H]

0.05

Extended Stellar Properties

Surface gravity (log g)

4.610 dex

Stellar density

2.330 g/cm³

Metallicity ratio

[Fe/H]

Distance

434.68 parsec

Light-years 1,417.75 ly

V-band magnitude

15.07 mag

Voyager-speed travel 25,001,984 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

2.272 mas

Total Proper Motion

3.558 mas/yr

PM Right Ascension

-1.15 mas/yr

PM Declination

-3.37 mas/yr

Galactic Cartesian (pc)

x = 0.314 · y = -0.692 · z = 0.650

Equatorial (J2000)

RA 294.44180° · Dec 40.55754°

Galactic ℓ, b

73.986° · 9.249°

Ecliptic λ, β

309.898° · 60.655°

HTM-20 index

1523114860