Key parameters at a glance
- A radius of 2.89 Earth radii
- A mass of 8.72 Earth masses
- Surface gravity around 1.04 g
- An orbital period of 20.035 days
- Semi-major axis 0.1587 AU
- Equilibrium temperature 967 K (694 °C)
- Distance from Earth 3,029.95 light-years
- Earth Similarity Index 0.245
- Travel time at Voyager 1 speed 53,433,225 years
1 sibling around Kepler-1921
Kepler-1921 b 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-1921 c | Super-Earth | 1.41 | 2.57 | 3.157 | 1,791 | 2023 |
| Kepler-1921 b this | Sub-Neptune | 2.89 | 8.72 | 20.035 | 967 | 2021 |
Kepler-1921 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#638of 1978
top 32.2%
This planet
2.89R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-1921 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.89 | 11.21 |
| Mass (M⊕) | 1.00 | 8.72 | 317.83 |
| Density (g/cm³) | 5.51 | 1.98 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.04 | 2.53 |
| Insolation (S⊕) | 1.00 | 216.20 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 239287963
Gaia DR2
Gaia DR2 2085204015173031552
Gaia DR3
Gaia DR3 2085204015173031552
System
Kepler-1921
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 20.03 Earth days (5.5% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1587 AU.
Transit Fingerprint
Depth
0.012 %
Duration
6.627 h
Impact parameter b
0.331
Rp / R★
0.010536
Transit midpoint (BJD)
2,454,978.4418
Photometric dip
Transit produces a flux drop of 124 ppm lasting ≈ 6.63 h.
Extended Orbital Architecture
Planet / star radius ratio
0.010536
Semi-major axis / stellar radius
23.390
Impact parameter (b)
0.331
Transit mid-time (BJD)
2,454,978.4418
Angular separation (arcsec)
0.17100
Eq. Temperature
967K
(694 °C)
Insolation (S⊕)
216.20
Earth = 1.00
Earth Similarity (ESI)
0.245
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.
Discovery Paper
Primary reference
Valizadegan et al. 2022Instrument
Kepler CCD Array
Publication
2022-02
Observation locale
Space
Discovery cohort
Planets confirmed in 2021 at Kepler (12 shown).
Host System: Kepler-1921
Spectral Class
F-type yellow-white
Effective Temperature
6,120 K — hotter than the Sun (5,778 K)
Estimated Age
3.39 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
2.000 R☉
Stellar Mass
1.251 M☉
Metallicity [Fe/H]
0.02
Extended Stellar Properties
Surface gravity (log g)
3.934 dex
Stellar density
0.603 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 15 bands
Astrometric Data
Parallax
1.048 mas
Total Proper Motion
15.166 mas/yr
PM Right Ascension
-4.45 mas/yr
PM Declination
-14.50 mas/yr
Galactic Cartesian (pc)
x = 0.354 · y = -0.605 · z = 0.713
Equatorial (J2000)
RA 300.31617° · Dec 45.49533°
Galactic ℓ, b
80.466° · 7.936°
Ecliptic λ, β
322.498° · 63.514°
HTM-20 index
-1129568641
Similar Worlds
HD 77946 b
Sub-Neptune · F-type yellow-white
Radius 2.90 R⊕ · 324.4 ly
Kepler-805 b
Sub-Neptune · F-type yellow-white
Radius 2.89 R⊕ · 2,082.5 ly
Kepler-631 b
Sub-Neptune · F-type yellow-white
Radius 2.90 R⊕ · 2,485.2 ly
Kepler-1239 b
Sub-Neptune · F-type yellow-white
Radius 2.90 R⊕ · 6,981.7 ly
Kepler-642 b
Sub-Neptune · F-type yellow-white
Radius 2.90 R⊕ · 2,549.2 ly
Kepler-1518 c
Sub-Neptune · F-type yellow-white
Radius 2.90 R⊕ · 2,946.9 ly