Key parameters at a glance
- A radius of 3.56 Earth radii
- A mass of 12.40 Earth masses
- Surface gravity around 0.98 g
- An orbital period of 29.671 days
- Semi-major axis 0.1607 AU
- Equilibrium temperature 393 K (119 °C)
- Distance from Earth 78.19 light-years
- Earth Similarity Index 0.528
- Travel time at Voyager 1 speed 1,378,801 years
- Almost certainly tidally locked to its host star given the close orbit
1 sibling around KOBE-1
KOBE-1 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| KOBE-1 b | Sub-Neptune | 2.91 | 8.80 | 8.540 | 594 | 2025 |
| KOBE-1 c this | Sub-Neptune | 3.56 | 12.40 | 29.671 | 393 | 2025 |
KOBE-1 c Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#151of 1978
top 7.6%
This planet
3.56R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | KOBE-1 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 3.56 | 11.21 |
| Mass (M⊕) | 1.00 | 12.40 | 317.83 |
| Density (g/cm³) | 5.51 | 1.51 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.98 | 2.53 |
| Insolation (S⊕) | 1.00 | 3.91 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 12.400 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HIP
HIP 5957
TIC
TIC 16917838
Gaia DR2
Gaia DR2 294517800251711616
Gaia DR3
Gaia DR3 294517800251711616
System
HIP 5957
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 29.67 Earth days (8.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1607 AU.
Extended Orbital Architecture
Semi-major axis / stellar radius
55.810
RV semi-amplitude (K)
3.500 m/s
Transit mid-time (BJD)
2,459,448.2000
Angular separation (arcsec)
6.70000
Eq. Temperature
393K
(119 °C)
Insolation (S⊕)
3.91
Earth = 1.00
Earth Similarity (ESI)
0.528
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
Balsalobre Ruza et al. 2025Instrument
CARMENES
Publication
2025-02
Observation locale
Ground
Discovery cohort
Planets confirmed in 2025 at Calar Alto Observatory (8 shown).
Host System: KOBE-1
Spectral Class
K-type orange
Effective Temperature
4,135 K — cooler than the Sun (5,778 K)
Estimated Age
—
Stellar Radius
0.619 R☉
Stellar Mass
0.629 M☉
Metallicity [Fe/H]
-0.01
Extended Stellar Properties
Surface gravity (log g)
5.070 dex
Stellar density
2.011 g/cm³
Systemic radial velocity
-23.10 km/s
Rotational v·sin i
2.00 km/s
Rotation period
37.40 days
Activity index (log R'HK)
-4.896
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 7 bands
Astrometric Data
Parallax
41.687 mas
Total Proper Motion
441.191 mas/yr
PM Right Ascension
429.06 mas/yr
PM Declination
-102.74 mas/yr
Galactic Cartesian (pc)
x = 0.854 · y = 0.297 · z = 0.428
Equatorial (J2000)
RA 19.16604° · Dec 25.33104°
Galactic ℓ, b
130.091° · -37.190°
Ecliptic λ, β
27.391° · 15.933°
HTM-20 index
1252749590
Similar Worlds
HIP 54373 c
Sub-Neptune · K-type orange
Radius 3.57 R⊕ · 61.0 ly
K2-8 b
Sub-Neptune · K-type orange
Radius 3.58 R⊕ · 1,316.1 ly
TOI-2076 c
Sub-Neptune · K-type orange
Radius 3.54 R⊕ · 136.7 ly
K2-285 c
Sub-Neptune · K-type orange
Radius 3.53 R⊕ · 505.4 ly
K2-283 b
Sub-Neptune · K-type orange
Radius 3.52 R⊕ · 1,314.1 ly
Kepler-1143 c
Sub-Neptune · K-type orange
Radius 3.60 R⊕ · 1,810.8 ly