Key parameters at a glance
- A radius of 2.47 Earth radii
- A mass of 6.66 Earth masses
- Surface gravity around 1.09 g
- An orbital period of 17.327 days
- Semi-major axis 0.1200 AU
- Equilibrium temperature 535 K (262 °C)
- Distance from Earth 2,529.92 light-years
- Earth Similarity Index 0.469
- Travel time at Voyager 1 speed 44,615,200 years
- Almost certainly tidally locked to its host star given the close orbit
3 siblings around Kepler-306
Kepler-306 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-306 b | Super-Earth | 1.52 | 2.92 | 4.646 | 830 | 2014 |
| Kepler-306 c | Sub-Neptune | 2.35 | 6.12 | 7.240 | 716 | 2014 |
| Kepler-306 d this | Sub-Neptune | 2.47 | 6.66 | 17.327 | 535 | 2014 |
| Kepler-306 e | Sub-Neptune | 2.27 | 5.77 | 44.841 | 390 | 2014 |
Kepler-306 d Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1226of 1978
top 61.9%
This planet
2.47R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-306 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.47 | 11.21 |
| Mass (M⊕) | 1.00 | 6.66 | 317.83 |
| Density (g/cm³) | 5.51 | 2.43 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.09 | 2.53 |
| Insolation (S⊕) | 1.00 | 21.98 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 121660143
Gaia DR2
Gaia DR2 2102067396802935680
Gaia DR3
Gaia DR3 2102067396802935680
System
Kepler-306
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 17.33 Earth days (4.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1200 AU.
Transit Fingerprint
Depth
0.080 %
Duration
4.777 h
Impact parameter b
0.900
Rp / R★
0.027607
Transit midpoint (BJD)
2,455,193.5089
Photometric dip
Transit produces a flux drop of 800 ppm lasting ≈ 4.78 h.
Extended Orbital Architecture
Planet / star radius ratio
0.027607
Semi-major axis / stellar radius
28.640
Impact parameter (b)
0.900
Transit mid-time (BJD)
2,455,193.5089
Angular separation (arcsec)
0.15500
Eq. Temperature
535K
(262 °C)
Insolation (S⊕)
21.98
Earth = 1.00
Earth Similarity (ESI)
0.469
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-306
Spectral Class
K-type orange
Effective Temperature
4,954 K — cooler than the Sun (5,778 K)
Estimated Age
2.63 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.719 R☉
Stellar Mass
0.750 M☉
Metallicity [Fe/H]
-0.13
Extended Stellar Properties
Surface gravity (log g)
4.611 dex
Stellar density
1.830 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
1.261 mas
Total Proper Motion
20.694 mas/yr
PM Right Ascension
3.18 mas/yr
PM Declination
-20.45 mas/yr
Galactic Cartesian (pc)
x = 0.241 · y = -0.720 · z = 0.651
Equatorial (J2000)
RA 288.53871° · Dec 40.61605°
Galactic ℓ, b
72.021° · 13.296°
Ecliptic λ, β
301.016° · 62.073°
HTM-20 index
-1467546318
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TOI-1244 b
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TOI-712 d
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K2-180 b
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TOI-1301.01
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