Key parameters at a glance
- A radius of 2.19 Earth radii
- A mass of 7.40 Earth masses
- Surface gravity around 1.55 g
- An orbital period of 6.327 days
- Semi-major axis 0.0664 AU
- Equilibrium temperature 1,049 K (776 °C)
- Distance from Earth 368.96 light-years
- Earth Similarity Index 0.260
- Travel time at Voyager 1 speed 6,506,564 years
K2-277 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1701of 1978
top 85.9%
This planet
2.19R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | K2-277 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.19 | 11.21 |
| Mass (M⊕) | 1.00 | 7.40 | 317.83 |
| Density (g/cm³) | 5.51 | 4.00 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.55 | 2.53 |
| Insolation (S⊕) | 1.00 | 195.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 7.400 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 404421005
Gaia DR2
Gaia DR2 3604866381969319040
Gaia DR3
Gaia DR3 3604866386264961792
System
K2-277
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 6.33 Earth days (1.7% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.0664 AU.
Transit Fingerprint
Depth
0.042 %
Duration
1.966 h
Impact parameter b
0.530
Rp / R★
0.020450
Transit midpoint (BJD)
2,457,303.4771
Photometric dip
Transit produces a flux drop of 418 ppm lasting ≈ 1.97 h.
Extended Orbital Architecture
Planet / star radius ratio
0.020450
Semi-major axis / stellar radius
14.680
Impact parameter (b)
0.530
Transit mid-time (BJD)
2,457,303.4771
Long. of periastron (ω)
46.00°
Angular separation (arcsec)
0.58700
Eq. Temperature
1,049K
(776 °C)
Insolation (S⊕)
195.00
Earth = 1.00
Earth Similarity (ESI)
0.260
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
Livingston et al. 2018Instrument
Kepler CCD Array
Publication
2018-12
Observation locale
Space
Discovery cohort
Planets confirmed in 2018 at K2 (12 shown).
Host System: K2-277
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,680 K — cooler than the Sun (5,778 K)
Estimated Age
4.90 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.973 R☉
Stellar Mass
0.974 M☉
Metallicity [Fe/H]
0.08
Extended Stellar Properties
Surface gravity (log g)
4.452 dex
Stellar density
1.500 g/cm³
Systemic radial velocity
7.52 km/s
Rotational v·sin i
2.30 km/s
Activity index (log R'HK)
-4.875
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
8.812 mas
Total Proper Motion
105.069 mas/yr
PM Right Ascension
-98.67 mas/yr
PM Declination
-36.10 mas/yr
Galactic Cartesian (pc)
x = -0.891 · y = -0.360 · z = -0.275
Equatorial (J2000)
RA 202.01619° · Dec -15.93797°
Galactic ℓ, b
315.663° · 46.026°
Ecliptic λ, β
206.263° · -6.232°
HTM-20 index
-420272133
Similar Worlds
Kepler-1109 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.19 R⊕ · 2,234.5 ly
K2-166 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.19 R⊕ · 1,555.4 ly
Kepler-51 e
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.18 R⊕ · 2,556.5 ly
Kepler-1016 b
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Radius 2.18 R⊕ · 4,575.4 ly
HD 158259 d
Sub-Neptune · G-type yellow (Sun-like)
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Kepler-1444 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.18 R⊕ · 1,042.6 ly