Key parameters at a glance
- A radius of 2.91 Earth radii
- A mass of 8.80 Earth masses
- Surface gravity around 1.04 g
- An orbital period of 8.540 days
- Semi-major axis 0.0701 AU
- Equilibrium temperature 594 K (321 °C)
- Distance from Earth 78.19 light-years
- Earth Similarity Index 0.399
- 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 b 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 this | Sub-Neptune | 2.91 | 8.80 | 8.540 | 594 | 2025 |
| KOBE-1 c | Sub-Neptune | 3.56 | 12.40 | 29.671 | 393 | 2025 |
KOBE-1 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#608of 1978
top 30.7%
This planet
2.91R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | KOBE-1 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.91 | 11.21 |
| Mass (M⊕) | 1.00 | 8.80 | 317.83 |
| Density (g/cm³) | 5.51 | 1.96 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.04 | 2.53 |
| Insolation (S⊕) | 1.00 | 20.56 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 8.800 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 8.54 Earth days (2.3% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0701 AU.
Extended Orbital Architecture
Semi-major axis / stellar radius
24.330
RV semi-amplitude (K)
3.750 m/s
Transit mid-time (BJD)
2,459,484.2600
Angular separation (arcsec)
2.92000
Eq. Temperature
594K
(321 °C)
Insolation (S⊕)
20.56
Earth = 1.00
Earth Similarity (ESI)
0.399
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
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Kepler-716 b
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TOI-824 b
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K2-266 d
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HD 15906 c
Sub-Neptune · K-type orange
Radius 2.93 R⊕ · 148.6 ly