Key parameters at a glance
- A radius of 2.75 Earth radii
- A mass of 8.00 Earth masses
- Surface gravity around 1.06 g
- An orbital period of 9.653 days
- Semi-major axis 0.0800 AU
- Equilibrium temperature 611 K (338 °C)
- Distance from Earth 1,417.75 light-years
- Earth Similarity Index 0.398
- 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 d 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 | 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 this | Sub-Neptune | 2.75 | 8.00 | 9.653 | 611 | 2014 |
Kepler-304 d Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#804of 1978
top 40.6%
This planet
2.75R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-304 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.75 | 11.21 |
| Mass (M⊕) | 1.00 | 8.00 | 317.83 |
| Density (g/cm³) | 5.51 | 2.11 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.06 | 2.53 |
| Insolation (S⊕) | 1.00 | 33.16 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 377909730
Gaia DR2
Gaia DR2 2076565805151925760
Gaia DR3
Gaia DR3 2076565805151925760
System
Kepler-304
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 9.65 Earth days (2.6% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0800 AU.
Transit Fingerprint
Depth
0.143 %
Duration
2.987 h
Impact parameter b
0.750
Rp / R★
0.031946
Transit midpoint (BJD)
2,454,967.8559
Photometric dip
Transit produces a flux drop of 1,432 ppm lasting ≈ 2.99 h.
Extended Orbital Architecture
Planet / star radius ratio
0.031946
Semi-major axis / stellar radius
25.950
Impact parameter (b)
0.750
Transit mid-time (BJD)
2,454,967.8559
Angular separation (arcsec)
0.18400
Eq. Temperature
611K
(338 °C)
Insolation (S⊕)
33.16
Earth = 1.00
Earth Similarity (ESI)
0.398
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.
Discovery Paper
Primary reference
Rowe et al. 2014Instrument
Kepler CCD Array
Publication
2014-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2014 at Kepler (12 shown).
Host System: Kepler-304
Spectral Class
K-type orange
Effective Temperature
4,731 K — cooler than the Sun (5,778 K)
Estimated Age
2.09 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.687 R☉
Stellar Mass
0.737 M☉
Metallicity [Fe/H]
0.03
Extended Stellar Properties
Surface gravity (log g)
4.635 dex
Stellar density
2.330 g/cm³
Metallicity ratio
[Fe/H]
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
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