Key parameters at a glance
- A radius of 2.50 Earth radii
- A mass of 6.80 Earth masses
- Surface gravity around 1.09 g
- An orbital period of 47.148 days
- Semi-major axis 0.2348 AU
- Equilibrium temperature 391 K (118 °C)
- Distance from Earth 675.09 light-years
- Earth Similarity Index 0.611
- Travel time at Voyager 1 speed 11,905,167 years
- Almost certainly tidally locked to its host star given the close orbit
Kepler-1521 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1168of 1978
top 59.0%
This planet
2.50R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-1521 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.50 | 11.21 |
| Mass (M⊕) | 1.00 | 6.80 | 317.83 |
| Density (g/cm³) | 5.51 | 2.39 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.09 | 2.53 |
| Insolation (S⊕) | 1.00 | 5.12 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 137817355
Gaia DR2
Gaia DR2 2051865551307698688
Gaia DR3
Gaia DR3 2051865551307698688
System
Kepler-1521
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 47.15 Earth days (12.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2348 AU.
Transit Fingerprint
Depth
0.111 %
Duration
3.067 h
Impact parameter b
0.307
Rp / R★
0.030428
Transit midpoint (BJD)
2,455,008.2685
Photometric dip
Transit produces a flux drop of 1,114 ppm lasting ≈ 3.07 h.
Extended Orbital Architecture
Planet / star radius ratio
0.030428
Semi-major axis / stellar radius
115.500
Impact parameter (b)
0.307
Transit mid-time (BJD)
2,455,008.2685
Angular separation (arcsec)
1.13000
Eq. Temperature
391K
(118 °C)
Insolation (S⊕)
5.12
Earth = 1.00
Earth Similarity (ESI)
0.611
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
Morton et al. 2016Instrument
Kepler CCD Array
Publication
2016-05
Observation locale
Space
Discovery cohort
Planets confirmed in 2016 at Kepler (12 shown).
Host System: Kepler-1521
Spectral Class
K-type orange
Effective Temperature
5,042 K — cooler than the Sun (5,778 K)
Estimated Age
4.47 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.760 R☉
Stellar Mass
0.810 M☉
Metallicity [Fe/H]
-0.05
Extended Stellar Properties
Surface gravity (log g)
4.590 dex
Stellar density
2.150 g/cm³
Systemic radial velocity
-21.95 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 17 bands
Astrometric Data
Parallax
4.803 mas
Total Proper Motion
24.564 mas/yr
PM Right Ascension
17.06 mas/yr
PM Declination
17.68 mas/yr
Galactic Cartesian (pc)
x = 0.305 · y = -0.729 · z = 0.613
Equatorial (J2000)
RA 292.69038° · Dec 37.83505°
Galactic ℓ, b
70.905° · 9.189°
Ecliptic λ, β
305.661° · 58.497°
HTM-20 index
1301378442
Similar Worlds
TOI-757 b
Sub-Neptune · K-type orange
Radius 2.50 R⊕ · 196.8 ly
Kepler-391 b
Sub-Neptune · K-type orange
Radius 2.50 R⊕ · 2,835.1 ly
Kepler-298 d
Sub-Neptune · K-type orange
Radius 2.50 R⊕ · 1,690.2 ly
Kepler-1168 b
Sub-Neptune · K-type orange
Radius 2.50 R⊕ · 2,454.9 ly
Kepler-659 b
Sub-Neptune · K-type orange
Radius 2.50 R⊕ · 2,356.9 ly
Kepler-543 b
Sub-Neptune · K-type orange
Radius 2.50 R⊕ · 723.4 ly