Key parameters at a glance
- A radius of 6.08 Earth radii
- A mass of 30.80 Earth masses
- Surface gravity around 0.83 g
- An orbital period of 25.942 days
- Semi-major axis 0.1650 AU
- Equilibrium temperature 587 K (314 °C)
- Distance from Earth 973.16 light-years
- Earth Similarity Index 0.292
- Travel time at Voyager 1 speed 17,161,701 years
2 siblings around K2-157
K2-157 c shares its host star with 2 other confirmed planets. Side-by-side measurements below.
K2-157 c Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#277of 574
top 48.1%
This planet
6.08R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | K2-157 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 6.08 | 11.21 |
| Mass (M⊕) | 1.00 | 30.80 | 317.83 |
| Density (g/cm³) | 5.51 | 0.75 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.83 | 2.53 |
| Insolation (S⊕) | 1.00 | 22.65 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 30.800 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
TIC
TIC 349445372
Gaia DR2
Gaia DR2 3596333042162818304
Gaia DR3
Gaia DR3 3596333042162818304
System
K2-157
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 25.94 Earth days (7.1% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1650 AU.
Extended Orbital Architecture
Semi-major axis / stellar radius
41.200
RV semi-amplitude (K)
7.170 m/s
Transit mid-time (BJD)
2,458,557.0200
Angular separation (arcsec)
0.55300
Eq. Temperature
587K
(314 °C)
Insolation (S⊕)
22.65
Earth = 1.00
Earth Similarity (ESI)
0.292
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
Castro Gonz & Aacute Lez et al. 2025Instrument
ESPRESSO
Publication
2025-04
Observation locale
Ground
Discovery cohort
Planets confirmed in 2025 at Paranal Observatory (8 shown).
Host System: K2-157
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,334 K — cooler than the Sun (5,778 K)
Estimated Age
8.80 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.860 R☉
Stellar Mass
0.890 M☉
Metallicity [Fe/H]
0.02
Extended Stellar Properties
Surface gravity (log g)
4.450 dex
Stellar density
1.679 g/cm³
Systemic radial velocity
43.45 km/s
Rotational v·sin i
3.00 km/s
Activity index (log R'HK)
-5.077
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
3.324 mas
Total Proper Motion
37.511 mas/yr
PM Right Ascension
36.72 mas/yr
PM Declination
-7.65 mas/yr
Galactic Cartesian (pc)
x = -0.993 · y = -0.065 · z = -0.101
Equatorial (J2000)
RA 183.75150° · Dec -5.78202°
Galactic ℓ, b
286.604° · 55.930°
Ecliptic λ, β
185.736° · -3.815°
HTM-20 index
1503740923
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