Key parameters at a glance
- A radius of 1.89 Earth radii
- A mass of 4.23 Earth masses
- Surface gravity around 1.18 g
- An orbital period of 58.035 days
- Semi-major axis 0.2610 AU
- Equilibrium temperature 486 K (213 °C)
- Distance from Earth 2,415.31 light-years
- Earth Similarity Index 0.563
- Travel time at Voyager 1 speed 42,593,916 years
2 siblings around Kepler-399
Kepler-399 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 |
|---|---|---|---|---|---|---|
| Kepler-399 b | Rocky Terrestrial | 0.96 | 0.84 | 14.425 | 773 | 2014 |
| Kepler-399 c | Super-Earth | 1.43 | 2.63 | 26.676 | 630 | 2014 |
| Kepler-399 d this | Super-Earth | 1.89 | 4.23 | 58.035 | 486 | 2014 |
Kepler-399 d Planet Profile
Physical Specs
Classification
Planet Type
Super-Earth
Discovery
Size rank in cohort
Rank by radius
#143of 1176
top 12.1%
This planet
1.89R⊕
Super-Earth median
1.60R⊕
Nearest-size peers
| Metric | Earth | Kepler-399 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 1.89 | 11.21 |
| Mass (M⊕) | 1.00 | 4.23 | 317.83 |
| Density (g/cm³) | 5.51 | 3.44 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.18 | 2.53 |
| Insolation (S⊕) | 1.00 | 5.57 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 172373693
Gaia DR2
Gaia DR2 2075060264503601280
Gaia DR3
Gaia DR3 2075060264503601280
System
Kepler-399
Percentile among Super-Earth cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 58.03 Earth days (15.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2610 AU.
Transit Fingerprint
Depth
0.081 %
Duration
5.435 h
Impact parameter b
0.190
Rp / R★
0.026282
Transit midpoint (BJD)
2,454,971.7332
Photometric dip
Transit produces a flux drop of 807 ppm lasting ≈ 5.44 h.
Extended Orbital Architecture
Planet / star radius ratio
0.026282
Semi-major axis / stellar radius
81.400
Impact parameter (b)
0.190
Transit mid-time (BJD)
2,454,971.7332
Angular separation (arcsec)
0.35200
Eq. Temperature
486K
(213 °C)
Insolation (S⊕)
5.57
Earth = 1.00
Earth Similarity (ESI)
0.563
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.
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-399
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,502 K — cooler than the Sun (5,778 K)
Estimated Age
3.98 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.680 R☉
Stellar Mass
0.902 M☉
Metallicity [Fe/H]
0.14
Extended Stellar Properties
Surface gravity (log g)
4.620 dex
Stellar density
3.030 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
0.734 mas
Total Proper Motion
9.259 mas/yr
PM Right Ascension
3.26 mas/yr
PM Declination
8.67 mas/yr
Galactic Cartesian (pc)
x = 0.374 · y = -0.660 · z = 0.652
Equatorial (J2000)
RA 299.50172° · Dec 40.67077°
Galactic ℓ, b
75.991° · 5.961°
Ecliptic λ, β
317.151° · 59.375°
HTM-20 index
-725349479
Similar Worlds
Kepler-1986 b
Super-Earth · G-type yellow (Sun-like)
Radius 1.89 R⊕ · 2,974.8 ly
K2-13 b
Super-Earth · G-type yellow (Sun-like)
Radius 1.89 R⊕ · 1,116.7 ly
Kepler-1534 b
Super-Earth · G-type yellow (Sun-like)
Radius 1.89 R⊕ · 3,610.5 ly
Kepler-171 d
Super-Earth · G-type yellow (Sun-like)
Radius 1.89 R⊕ · 2,817.5 ly
Kepler-371 b
Super-Earth · G-type yellow (Sun-like)
Radius 1.89 R⊕ · 2,652.3 ly
Kepler-1917 b
Super-Earth · G-type yellow (Sun-like)
Radius 1.89 R⊕ · 2,964.9 ly