Key parameters at a glance
- A radius of 1.59 Earth radii
- A mass of 6.49 Earth masses
- Surface gravity around 2.57 g
- An orbital period of 2.225 days
- Semi-major axis 0.0326 AU
- Equilibrium temperature 1,278 K (1005 °C)
- Distance from Earth 293.72 light-years
- Earth Similarity Index 0.207
- Travel time at Voyager 1 speed 5,179,817 years
K2-291 b Planet Profile
Physical Specs
Classification
Planet Type
Super-Earth
Discovery
Size rank in cohort
Rank by radius
#600of 1176
top 50.9%
This planet
1.59R⊕
Super-Earth median
1.60R⊕
Nearest-size peers
| Metric | Earth | K2-291 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 1.59 | 11.21 |
| Mass (M⊕) | 1.00 | 6.49 | 317.83 |
| Density (g/cm³) | 5.51 | 8.84 | 1.33 |
| Surface Gravity (g) | 1.00 | 2.57 | 2.53 |
| Insolation (S⊕) | 1.00 | 633.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 6.490 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
HD
HD 285181
TIC
TIC 27039476
Gaia DR2
Gaia DR2 3409148746676599168
Gaia DR3
Gaia DR3 3409148746676599168
System
K2-291
Percentile among Super-Earth cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 2.23 Earth days (0.6% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0326 AU.
Transit Fingerprint
Depth
0.028 %
Duration
1.719 h
Impact parameter b
0.646
Rp / R★
0.016140
Transit midpoint (BJD)
2,457,830.0616
Photometric dip
Transit produces a flux drop of 284 ppm lasting ≈ 1.72 h.
Extended Orbital Architecture
Planet / star radius ratio
0.016140
Semi-major axis / stellar radius
7.794
Impact parameter (b)
0.646
RV semi-amplitude (K)
3.330 m/s
Transit mid-time (BJD)
2,457,830.0616
Long. of periastron (ω)
0.00°
Angular separation (arcsec)
0.36200
Eq. Temperature
1,278K
(1005 °C)
Insolation (S⊕)
633.00
Earth = 1.00
Earth Similarity (ESI)
0.207
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Radial velocity
Stellar wobble has been measured spectroscopically.
Discovery Paper
Primary reference
Kosiarek et al. 2019Instrument
Kepler CCD Array
Publication
2019-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2019 at K2 (12 shown).
Host System: K2-291
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,520 K — cooler than the Sun (5,778 K)
Estimated Age
3.72 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.899 R☉
Stellar Mass
0.934 M☉
Metallicity [Fe/H]
0.08
Extended Stellar Properties
Surface gravity (log g)
4.500 dex
Stellar density
1.770 g/cm³
Systemic radial velocity
25.13 km/s
Rotational v·sin i
2.00 km/s
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
11.076 mas
Total Proper Motion
101.824 mas/yr
PM Right Ascension
30.71 mas/yr
PM Declination
-97.08 mas/yr
Galactic Cartesian (pc)
x = 0.218 · y = 0.904 · z = 0.367
Equatorial (J2000)
RA 76.44594° · Dec 21.54820°
Galactic ℓ, b
181.179° · -11.582°
Ecliptic λ, β
77.402° · -1.300°
HTM-20 index
752035244
Similar Worlds
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Super-Earth · G-type yellow (Sun-like)
Radius 1.59 R⊕ · 3,051.0 ly
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Kepler-370 b
Super-Earth · G-type yellow (Sun-like)
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