Kepler-1858 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1858 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1858, located approximately 2717.1 light-years (833.06 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0735% across the stellar disk), this world measures 2.422 Earth radii and has a measured mass of 6.44 Earth masses. Combining its mass and radius yields a mean bulk density of 2.5 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.1 g⊕ (10.79 m/s²), and an escape velocity of 18.2 km/s.
In its orbital architecture around Kepler-1858, Kepler-1858 b completes one full revolution every 88.072 Earth days at a semi-major axis of 0.3575 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 44.2 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.422 R⊕, Kepler-1858 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star Kepler-1858 is classified as a stellar host with an effective photospheric temperature of 4,939 K, a radius of 0.819 R☉, a mass of 0.785 M☉, an estimated bolometric luminosity of 0.358 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.7 Gyr and a metallicity of [Fe/H] = 0.16 dex (metal-rich relative to the Sun). From Earth, Kepler-1858 shines at apparent V-band magnitude 15.959 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-1858 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,939 K |
| Stellar Radius | 0.8190 R☉ |
| Stellar Mass | 0.7850 M☉ |
| Bolometric Luminosity | 0.358 L☉ |
| Metallicity [Fe/H] | 0.160 dex |
| Stellar Age | 0.700 Gyr |
| Apparent Magnitude | V: 15.959 · G: 15.641 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.357500 AU |
| Orbital Period | 88.072 days |
| Mean Orbital Velocity | 44.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.7900° |
| Mean Bulk Density | 2.5 g/cm³ (18.2 km/s vesc) |
| Insolation Flux | 2.7900 S⊕ (~3,797 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2717.100 LY (833.055 pc) |