Key parameters at a glance
- A radius of 2.05 Earth radii
- A mass of 4.86 Earth masses
- Surface gravity around 1.16 g
- An orbital period of 2.298 days
- Semi-major axis 0.0284 AU
- Equilibrium temperature 830 K (557 °C)
- Distance from Earth 253.39 light-years
- Earth Similarity Index 0.328
- Travel time at Voyager 1 speed 4,468,474 years
- Almost certainly tidally locked to its host star given the close orbit
K2-321 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1886of 1978
top 95.3%
This planet
2.05R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | K2-321 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.05 | 11.21 |
| Mass (M⊕) | 1.00 | 4.86 | 317.83 |
| Density (g/cm³) | 5.51 | 3.09 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.16 | 2.53 |
| Insolation (S⊕) | 1.00 | 68.55 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 277833995
Gaia DR2
Gaia DR2 3856449627544923392
Gaia DR3
Gaia DR3 3856449627544923392
System
K2-321
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 2.30 Earth days (0.6% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.0284 AU.
Transit Fingerprint
Depth
0.099 %
Duration
1.147 h
Impact parameter b
0.470
Rp / R★
0.031500
Transit midpoint (BJD)
2,458,141.2676
Photometric dip
Transit produces a flux drop of 992 ppm lasting ≈ 1.15 h.
Extended Orbital Architecture
Planet / star radius ratio
0.031500
Semi-major axis / stellar radius
10.250
Impact parameter (b)
0.470
Transit mid-time (BJD)
2,458,141.2676
Long. of periastron (ω)
45.00°
Angular separation (arcsec)
0.36500
Eq. Temperature
830K
(557 °C)
Insolation (S⊕)
68.55
Earth = 1.00
Earth Similarity (ESI)
0.328
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
Castro Gonz Aacute Lez et al. 2020Instrument
Kepler CCD Array
Publication
2020-12
Observation locale
Space
Discovery cohort
Planets confirmed in 2020 at K2 (12 shown).
Host System: K2-321
Spectral Class
K-type orange
Effective Temperature
3,750 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.595 R☉
Stellar Mass
0.578 M☉
Metallicity [Fe/H]
0.15
Extended Stellar Properties
Surface gravity (log g)
4.650 dex
Stellar density
3.860 g/cm³
Systemic radial velocity
-43.90 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 17 bands
Astrometric Data
Parallax
12.843 mas
Total Proper Motion
120.488 mas/yr
PM Right Ascension
50.92 mas/yr
PM Declination
-109.20 mas/yr
Galactic Cartesian (pc)
x = -0.916 · y = 0.400 · z = 0.044
Equatorial (J2000)
RA 156.40550° · Dec 2.51388°
Galactic ℓ, b
241.809° · 47.321°
Ecliptic λ, β
157.224° · -6.824°
HTM-20 index
-493226519
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