Key parameters at a glance
- A radius of 2.00 Earth radii
- A mass of 4.66 Earth masses
- Surface gravity around 1.17 g
- An orbital period of 24.571 days
- Semi-major axis 0.1560 AU
- Equilibrium temperature 505 K (232 °C)
- Distance from Earth 1,035.54 light-years
- Earth Similarity Index 0.534
- Travel time at Voyager 1 speed 18,261,783 years
- Almost certainly tidally locked to its host star given the close orbit
1 sibling around Kepler-261
Kepler-261 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-261 b | Sub-Neptune | 2.18 | 5.39 | 10.381 | 672 | 2014 |
| Kepler-261 c this | Sub-Neptune | 2.00 | 4.66 | 24.571 | 505 | 2014 |
Kepler-261 c Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1955of 1978
top 98.8%
This planet
2.00R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-261 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.00 | 11.21 |
| Mass (M⊕) | 1.00 | 4.66 | 317.83 |
| Density (g/cm³) | 5.51 | 3.20 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.17 | 2.53 |
| Insolation (S⊕) | 1.00 | 14.51 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 137148674
Gaia DR2
Gaia DR2 2052528625536778624
Gaia DR3
Gaia DR3 2052528625536778624
System
Kepler-261
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 24.57 Earth days (6.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1560 AU.
Transit Fingerprint
Depth
0.075 %
Duration
2.761 h
Impact parameter b
0.190
Rp / R★
0.024880
Transit midpoint (BJD)
2,454,968.8741
Photometric dip
Transit produces a flux drop of 754 ppm lasting ≈ 2.76 h.
Extended Orbital Architecture
Planet / star radius ratio
0.024880
Semi-major axis / stellar radius
51.400
Impact parameter (b)
0.190
Transit mid-time (BJD)
2,454,968.8741
Angular separation (arcsec)
0.49100
Eq. Temperature
505K
(232 °C)
Insolation (S⊕)
14.51
Earth = 1.00
Earth Similarity (ESI)
0.534
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-261
Spectral Class
K-type orange
Effective Temperature
5,098 K — cooler than the Sun (5,778 K)
Estimated Age
0.87 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.794 R☉
Stellar Mass
0.834 M☉
Metallicity [Fe/H]
0.16
Extended Stellar Properties
Surface gravity (log g)
4.561 dex
Stellar density
1.910 g/cm³
Metallicity ratio
[M/H]
Multi-band Host Photometry — 17 bands
Astrometric Data
Parallax
3.121 mas
Total Proper Motion
15.371 mas/yr
PM Right Ascension
-4.20 mas/yr
PM Declination
14.79 mas/yr
Galactic Cartesian (pc)
x = 0.289 · y = -0.738 · z = 0.610
Equatorial (J2000)
RA 291.36473° · Dec 37.60924°
Galactic ℓ, b
70.219° · 10.020°
Ecliptic λ, β
303.612° · 58.581°
HTM-20 index
1682083973
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