Key parameters at a glance
- A radius of 2.86 Earth radii
- A mass of 8.55 Earth masses
- Surface gravity around 1.05 g
- An orbital period of 20.957 days
- Semi-major axis 0.1260 AU
- Equilibrium temperature 363 K (90 °C)
- Distance from Earth 1,480.08 light-years
- Earth Similarity Index 0.615
- Travel time at Voyager 1 speed 26,101,203 years
- Almost certainly tidally locked to its host star given the close orbit
3 siblings around Kepler-1388
Kepler-1388 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-1388 c | Sub-Neptune | 2.26 | 5.73 | 5.536 | 566 | 2016 |
| Kepler-1388 b | Sub-Neptune | 2.59 | 7.22 | 12.285 | 434 | 2016 |
| Kepler-1388 d this | Sub-Neptune | 2.86 | 8.55 | 20.957 | 363 | 2016 |
| Kepler-1388 e | Sub-Neptune | 2.46 | 6.62 | 37.633 | 299 | 2016 |
Kepler-1388 d Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#671of 1978
top 33.9%
This planet
2.86R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-1388 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.86 | 11.21 |
| Mass (M⊕) | 1.00 | 8.55 | 317.83 |
| Density (g/cm³) | 5.51 | 2.01 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.05 | 2.53 |
| Insolation (S⊕) | 1.00 | 8.66 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 164524311
Gaia DR2
Gaia DR2 2107617246162706048
Gaia DR3
Gaia DR3 2107617246162706048
System
Kepler-1388
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 20.96 Earth days (5.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1260 AU.
Transit Fingerprint
Depth
0.192 %
Duration
3.558 h
Impact parameter b
0.112
Rp / R★
0.042526
Transit midpoint (BJD)
2,454,972.0875
Photometric dip
Transit produces a flux drop of 1,918 ppm lasting ≈ 3.56 h.
Extended Orbital Architecture
Planet / star radius ratio
0.042526
Semi-major axis / stellar radius
47.330
Impact parameter (b)
0.112
Transit mid-time (BJD)
2,454,972.0875
Angular separation (arcsec)
0.27800
Eq. Temperature
363K
(90 °C)
Insolation (S⊕)
8.66
Earth = 1.00
Earth Similarity (ESI)
0.615
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — liquid water is physically possible with adequate atmospheric pressure. Close-orbiting tidally-locked around a cool host.
Discovery Paper
Primary reference
Morton et al. 2016Instrument
Kepler CCD Array
Publication
2016-05
Observation locale
Space
Discovery cohort
Planets confirmed in 2016 at Kepler (12 shown).
Host System: Kepler-1388
Spectral Class
K-type orange
Effective Temperature
4,098 K — cooler than the Sun (5,778 K)
Estimated Age
4.47 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.610 R☉
Stellar Mass
0.630 M☉
Metallicity [Fe/H]
0.02
Extended Stellar Properties
Surface gravity (log g)
4.670 dex
Stellar density
3.828 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
2.175 mas
Total Proper Motion
16.932 mas/yr
PM Right Ascension
-7.32 mas/yr
PM Declination
-15.27 mas/yr
Galactic Cartesian (pc)
x = 0.157 · y = -0.661 · z = 0.733
Equatorial (J2000)
RA 283.33602° · Dec 47.17445°
Galactic ℓ, b
76.884° · 19.232°
Ecliptic λ, β
296.450° · 69.392°
HTM-20 index
1364629176
Similar Worlds
Kepler-304 b
Sub-Neptune · K-type orange
Radius 2.86 R⊕ · 1,417.7 ly
TOI-5789 c
Sub-Neptune · K-type orange
Radius 2.86 R⊕ · 66.7 ly
HD 110067 d
Sub-Neptune · K-type orange
Radius 2.85 R⊕ · 104.9 ly
HIP 54373 b
Sub-Neptune · K-type orange
Radius 2.87 R⊕ · 61.0 ly
K2-199 c
Sub-Neptune · K-type orange
Radius 2.85 R⊕ · 350.7 ly
Kepler-1684 b
Sub-Neptune · K-type orange
Radius 2.87 R⊕ · 2,028.7 ly