Kepler-1558 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1558 b is a confirmed sub-earth exoplanet orbiting the star Kepler-1558, located approximately 1062.4 light-years (325.74 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0062% across the stellar disk), this world measures 0.68 Earth radii and has a measured mass of 0.244 Earth masses. Combining its mass and radius yields a mean bulk density of 4.28 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.53 g⊕ (5.2 m/s²), and an escape velocity of 6.7 km/s.
In its orbital architecture around Kepler-1558, Kepler-1558 b completes one full revolution every 3.505 Earth days at a semi-major axis of 0.04278 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 132.8 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.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1019 K (+746°C / +1375°F) and receiving 189.89 S⊕ (~258,435 W/m²), Kepler-1558 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1558 is classified as a stellar host with an effective photospheric temperature of 5,101 K, a radius of 0.79 R☉, a mass of 0.83 M☉, an estimated bolometric luminosity of 0.379 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.9 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-1558 shines at apparent V-band magnitude 13.809 (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-1558 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,101 K |
| Stellar Radius | 0.7900 R☉ |
| Stellar Mass | 0.8300 M☉ |
| Bolometric Luminosity | 0.379 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 4.900 Gyr |
| Apparent Magnitude | V: 13.809 · G: 13.600 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.042780 AU |
| Orbital Period | 3.505 days |
| Mean Orbital Velocity | 132.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.6600° |
| Mean Bulk Density | 4.28 g/cm³ (6.7 km/s vesc) |
| Insolation Flux | 189.8860 S⊕ (~258,435 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1062.400 LY (325.737 pc) |