Key parameters at a glance
- A radius of 5.94 Earth radii
- A mass of 654.00 Earth masses
- Surface gravity around 18.55 g
- An orbital period of 148.272 days
- Semi-major axis 0.5456 AU
- Equilibrium temperature 321 K (48 °C)
- Distance from Earth 5,692.89 light-years
- Earth Similarity Index 0.502
- Travel time at Voyager 1 speed 100,394,108 years
2 siblings around Kepler-281
Kepler-281 d shares its host star with 2 other confirmed planets. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| Kepler-281 b | Sub-Neptune | 2.82 | 324.00 | 14.646 | 694 | 2014 |
| Kepler-281 c | Neptune-like | 5.31 | 161.12 | 36.337 | 513 | 2014 |
| Kepler-281 d this | Neptune-like | 5.94 | 654.00 | 148.272 | 321 | 2021 |
Kepler-281 d Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#290of 574
top 50.3%
This planet
5.94R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | Kepler-281 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 5.94 | 11.21 |
| Mass (M⊕) | 1.00 | 654.00 | 317.83 |
| Density (g/cm³) | 5.51 | 12.30 | 1.33 |
| Surface Gravity (g) | 1.00 | 18.55 | 2.53 |
| Insolation (S⊕) | 1.00 | 2.51 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 654.000 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 270858032
Gaia DR2
Gaia DR2 2078404532186285568
Gaia DR3
Gaia DR3 2078404532186285568
System
Kepler-281
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 148.27 Earth days (40.6% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.5456 AU.
Transit Fingerprint
Depth
0.171 %
Duration
4.192 h
Impact parameter b
1.140
Rp / R★
0.046823
Transit midpoint (BJD)
2,454,971.0056
Photometric dip
Transit produces a flux drop of 1,707 ppm lasting ≈ 4.19 h.
Extended Orbital Architecture
Planet / star radius ratio
0.046823
Semi-major axis / stellar radius
74.000
Impact parameter (b)
1.140
Transit mid-time (BJD)
2,454,971.0056
Angular separation (arcsec)
0.31300
Eq. Temperature
321K
(48 °C)
Insolation (S⊕)
2.51
Earth = 1.00
Earth Similarity (ESI)
0.502
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — liquid water is physically possible with adequate atmospheric pressure.
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-281
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,717 K — cooler than the Sun (5,778 K)
Estimated Age
0.60 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.884 R☉
Stellar Mass
0.984 M☉
Metallicity [Fe/H]
0.00
Extended Stellar Properties
Surface gravity (log g)
4.538 dex
Stellar density
2.959 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
0.545 mas
Total Proper Motion
11.298 mas/yr
PM Right Ascension
-6.44 mas/yr
PM Declination
-9.29 mas/yr
Galactic Cartesian (pc)
x = 0.290 · y = -0.648 · z = 0.704
Equatorial (J2000)
RA 294.10815° · Dec 44.77065°
Galactic ℓ, b
77.669° · 11.413°
Ecliptic λ, β
312.683° · 64.678°
HTM-20 index
-1670214005
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Kepler-700 b
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Radius 5.99 R⊕ · 4,865.5 ly