Key parameters at a glance
- A radius of 0.93 Earth radii
- A mass of 0.75 Earth masses
- Surface gravity around 0.87 g
- An orbital period of 4.081 days
- Semi-major axis 0.0440 AU
- Equilibrium temperature 755 K (482 °C)
- Distance from Earth 578.45 light-years
- Earth Similarity Index 0.426
- Travel time at Voyager 1 speed 10,201,035 years
- Almost certainly tidally locked to its host star given the close orbit
2 siblings around Kepler-398
Kepler-398 b 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-398 b this | Rocky Terrestrial | 0.93 | 0.75 | 4.081 | 755 | 2014 |
| Kepler-398 d | Rocky Terrestrial | 0.88 | 0.62 | 6.834 | 636 | 2016 |
| Kepler-398 c | Rocky Terrestrial | 1.01 | 1.01 | 11.419 | 536 | 2014 |
Kepler-398 b Planet Profile
Physical Specs
Classification
Planet Type
Rocky Terrestrial
Discovery
Size rank in cohort
Rank by radius
#391of 570
top 68.4%
This planet
0.93R⊕
Rocky Terrestrial median
1.01R⊕
Nearest-size peers
| Metric | Earth | Kepler-398 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 0.93 | 11.21 |
| Mass (M⊕) | 1.00 | 0.75 | 317.83 |
| Density (g/cm³) | 5.51 | 5.12 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.87 | 2.53 |
| Insolation (S⊕) | 1.00 | 81.29 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 137155210
Gaia DR2
Gaia DR2 2053457644144430848
Gaia DR3
Gaia DR3 2053457644144430848
System
Kepler-398
Percentile among Rocky Terrestrial cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 4.08 Earth days (1.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0440 AU.
Transit Fingerprint
Depth
0.016 %
Duration
2.287 h
Impact parameter b
0.870
Rp / R★
0.013541
Transit midpoint (BJD)
2,454,966.8580
Photometric dip
Transit produces a flux drop of 163 ppm lasting ≈ 2.29 h.
Extended Orbital Architecture
Planet / star radius ratio
0.013541
Semi-major axis / stellar radius
6.930
Impact parameter (b)
0.870
Transit mid-time (BJD)
2,454,966.8580
Angular separation (arcsec)
0.24800
Eq. Temperature
755K
(482 °C)
Insolation (S⊕)
81.29
Earth = 1.00
Earth Similarity (ESI)
0.426
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-398
Spectral Class
K-type orange
Effective Temperature
4,493 K — cooler than the Sun (5,778 K)
Estimated Age
2.34 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.613 R☉
Stellar Mass
0.649 M☉
Metallicity [Fe/H]
0.05
Extended Stellar Properties
Surface gravity (log g)
4.689 dex
Stellar density
0.378 g/cm³
Metallicity ratio
[M/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
5.610 mas
Total Proper Motion
44.396 mas/yr
PM Right Ascension
30.66 mas/yr
PM Declination
-32.11 mas/yr
Galactic Cartesian (pc)
x = 0.279 · y = -0.709 · z = 0.647
Equatorial (J2000)
RA 291.46885° · Dec 40.34370°
Galactic ℓ, b
72.746° · 11.166°
Ecliptic λ, β
305.346° · 61.174°
HTM-20 index
1642014504
Similar Worlds
Kepler-1387 b
Rocky Terrestrial · K-type orange
Radius 0.93 R⊕ · 1,485.2 ly
Kepler-779 b
Rocky Terrestrial · K-type orange
Radius 0.92 R⊕ · 923.5 ly
Kepler-1367 b
Rocky Terrestrial · K-type orange
Radius 0.92 R⊕ · 1,309.5 ly
Kepler-1957 b
Rocky Terrestrial · K-type orange
Radius 0.94 R⊕ · 1,503.2 ly
Kepler-1049 b
Rocky Terrestrial · K-type orange
Radius 0.95 R⊕ · 528.4 ly
EPIC 201757695.02
Rocky Terrestrial · K-type orange
Radius 0.91 R⊕ · 1,883.9 ly