Key parameters at a glance
- A radius of 12.11 Earth radii
- A mass of 403.63 Earth masses
- Surface gravity around 2.75 g
- An orbital period of 3.526 days
- Semi-major axis 0.0433 AU
- Equilibrium temperature 1,070 K (797 °C)
- Distance from Earth 2,238.36 light-years
- Earth Similarity Index 0.137
- Travel time at Voyager 1 speed 39,473,414 years
- Almost certainly tidally locked to its host star given the close orbit
Kepler-428 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#1448of 1771
top 81.7%
This planet
12.11R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | Kepler-428 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 12.11 | 11.21 |
| Mass (M⊕) | 1.00 | 403.63 | 317.83 |
| Density (g/cm³) | 5.51 | 1.02 | 1.33 |
| Surface Gravity (g) | 1.00 | 2.75 | 2.53 |
| Insolation (S⊕) | 1.00 | 195.09 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 403.630 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 122596693
Gaia DR2
Gaia DR2 2101186168296277376
Gaia DR3
Gaia DR3 2101186168296277376
System
Kepler-428
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 3.53 Earth days (1.0% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0433 AU.
Transit Fingerprint
Depth
2.234 %
Duration
2.614 h
Impact parameter b
0.130
Rp / R★
0.138400
Transit midpoint (BJD)
2,455,003.0480
Photometric dip
Transit produces a flux drop of 22,335 ppm lasting ≈ 2.61 h.
Extended Orbital Architecture
Planet / star radius ratio
0.138400
Semi-major axis / stellar radius
11.650
Impact parameter (b)
0.130
RV semi-amplitude (K)
188.000 m/s
Transit mid-time (BJD)
2,455,003.0480
Angular separation (arcsec)
0.06310
Eq. Temperature
1,070K
(797 °C)
Insolation (S⊕)
195.09
Earth = 1.00
Earth Similarity (ESI)
0.137
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.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Radial velocity
Stellar wobble has been measured spectroscopically.
Discovery Paper
Primary reference
H Eacute Brard et al. 2014Instrument
Kepler CCD Array
Publication
2014-12
Observation locale
Space
Discovery cohort
Planets confirmed in 2014 at Kepler (12 shown).
Host System: Kepler-428
Spectral Class
K-type orange
Effective Temperature
5,150 K — cooler than the Sun (5,778 K)
Estimated Age
5.00 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.800 R☉
Stellar Mass
0.870 M☉
Metallicity [Fe/H]
0.09
Extended Stellar Properties
Surface gravity (log g)
4.571 dex
Stellar density
1.704 g/cm³
Systemic radial velocity
-21.30 km/s
Rotational v·sin i
2.00 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
1.429 mas
Total Proper Motion
15.922 mas/yr
PM Right Ascension
1.32 mas/yr
PM Declination
-15.87 mas/yr
Galactic Cartesian (pc)
x = 0.267 · y = -0.711 · z = 0.650
Equatorial (J2000)
RA 290.58174° · Dec 40.57731°
Galactic ℓ, b
72.659° · 11.875°
Ecliptic λ, β
304.146° · 61.599°
HTM-20 index
-1059387765
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