Key parameters at a glance
- A radius of 2.51 Earth radii
- A mass of 6.85 Earth masses
- Surface gravity around 1.09 g
- An orbital period of 105.356 days
- Semi-major axis 0.4010 AU
- Equilibrium temperature 204 K (-69 °C)
- Distance from Earth 1,776.14 light-years
- Earth Similarity Index 0.591
- Travel time at Voyager 1 speed 31,322,248 years
1 sibling around Kepler-309
Kepler-309 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| Kepler-309 b | Super-Earth | 1.56 | 3.05 | 5.924 | 531 | 2014 |
| Kepler-309 c this | Sub-Neptune | 2.51 | 6.85 | 105.356 | 204 | 2014 |
Kepler-309 c Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1159of 1978
top 58.5%
This planet
2.51R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-309 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.51 | 11.21 |
| Mass (M⊕) | 1.00 | 6.85 | 317.83 |
| Density (g/cm³) | 5.51 | 2.38 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.09 | 2.53 |
| Insolation (S⊕) | 1.00 | 2.14 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 273373488
Gaia DR2
Gaia DR2 2086315415269037696
Gaia DR3
Gaia DR3 2086315415269037696
System
Kepler-309
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 105.36 Earth days (28.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.4010 AU.
Transit Fingerprint
Depth
0.121 %
Duration
3.658 h
Impact parameter b
0.400
Rp / R★
0.039119
Transit midpoint (BJD)
2,454,971.6839
Photometric dip
Transit produces a flux drop of 1,210 ppm lasting ≈ 3.66 h.
Extended Orbital Architecture
Planet / star radius ratio
0.039119
Semi-major axis / stellar radius
79.000
Impact parameter (b)
0.400
Transit mid-time (BJD)
2,454,971.6839
Angular separation (arcsec)
0.73600
Eq. Temperature
204K
(-69 °C)
Insolation (S⊕)
2.14
Earth = 1.00
Earth Similarity (ESI)
0.591
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — surface water would be frozen.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Transit timing variations
Gravitational interactions from neighbours have been detected.
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-309
Spectral Class
M-type red dwarf
Effective Temperature
4,713 K — cooler than the Sun (5,778 K)
Estimated Age
3.02 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.721 R☉
Stellar Mass
0.816 M☉
Metallicity [Fe/H]
0.27
Extended Stellar Properties
Surface gravity (log g)
4.612 dex
Stellar density
1.940 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
1.808 mas
Total Proper Motion
35.063 mas/yr
PM Right Ascension
3.70 mas/yr
PM Declination
34.87 mas/yr
Galactic Cartesian (pc)
x = 0.315 · y = -0.605 · z = 0.731
Equatorial (J2000)
RA 297.50989° · Dec 46.96141°
Galactic ℓ, b
80.771° · 10.349°
Ecliptic λ, β
319.983° · 65.695°
HTM-20 index
1124262296
Similar Worlds
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TOI-1266 b
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HD 238090 b
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