Key parameters at a glance
- A radius of 15.87 Earth radii
- A mass of 187.52 Earth masses
- Surface gravity around 0.74 g
- An orbital period of 3.522 days
- Semi-major axis 0.0474 AU
- Equilibrium temperature 1,680 K (1407 °C)
- Distance from Earth 3,332.89 light-years
- Earth Similarity Index 0.061
- Travel time at Voyager 1 speed 58,775,517 years
Kepler-8 b Planet Profile
Physical Specs
Classification
Planet Type
Gas Giant
Discovery
Size rank in cohort
Rank by radius
#170of 1771
top 9.5%
This planet
15.87R⊕
Gas Giant median
13.52R⊕
Nearest-size peers
| Metric | Earth | Kepler-8 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 15.87 | 11.21 |
| Mass (M⊕) | 1.00 | 187.52 | 317.83 |
| Density (g/cm³) | 5.51 | 0.27 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.74 | 2.53 |
| Insolation (S⊕) | 1.00 | 1,444.88 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 187.520 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 123233041
Gaia DR2
Gaia DR2 2116730994965905280
Gaia DR3
Gaia DR3 2116730994965905280
System
Kepler-8
Percentile among Gas Giant cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 3.52 Earth days (1.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0474 AU.
Transit Fingerprint
Depth
0.915 %
Duration
3.191 h
Impact parameter b
0.719
Rp / R★
0.095751
Transit midpoint (BJD)
2,454,954.1193
Photometric dip
Transit produces a flux drop of 9,146 ppm lasting ≈ 3.19 h.
Extended Orbital Architecture
Planet / star radius ratio
0.095751
Semi-major axis / stellar radius
6.854
Impact parameter (b)
0.719
RV semi-amplitude (K)
68.400 m/s
Occultation depth
0.003 ppm
Transit mid-time (BJD)
2,454,954.1193
Sky-projected obliquity (λ)
-26.40°
Angular separation (arcsec)
0.04640
Eq. Temperature
1,680K
(1407 °C)
Insolation (S⊕)
1,444.88
Earth = 1.00
Earth Similarity (ESI)
0.061
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Radial velocity
Stellar wobble has been measured spectroscopically.
Orbital-brightness modulation
Host star brightness varies with the planet's orbit.
Discovery Paper
Primary reference
Jenkins et al. 2010Instrument
Kepler CCD Array
Publication
2010-12
Observation locale
Space
Discovery cohort
Planets confirmed in 2010 at Kepler (11 shown).
Host System: Kepler-8
Spectral Class
F-type yellow-white
Effective Temperature
6,213 K — hotter than the Sun (5,778 K)
Estimated Age
3.47 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
1.486 R☉
Stellar Mass
1.213 M☉
Metallicity [Fe/H]
-0.06
Extended Stellar Properties
Surface gravity (log g)
4.174 dex
Stellar density
0.654 g/cm³
Systemic radial velocity
-52.72 km/s
Rotational v·sin i
10.50 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
0.950 mas
Total Proper Motion
4.425 mas/yr
PM Right Ascension
2.20 mas/yr
PM Declination
3.84 mas/yr
Galactic Cartesian (pc)
x = 0.144 · y = -0.724 · z = 0.675
Equatorial (J2000)
RA 281.28813° · Dec 42.45110°
Galactic ℓ, b
71.659° · 19.013°
Ecliptic λ, β
290.063° · 65.106°
HTM-20 index
-1630646154
Observation Record
Photometric series
1
RV measurements
1
Archive notes
1
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