Kepler-58 d
Astrophysical Synthesis & Habitability Characterization
Kepler-58 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-58, located approximately 3161.3 light-years (969.25 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0572% across the stellar disk), this world measures 2.94 Earth radii and has a measured mass of 245.343 Earth masses (0.77 Jupiter masses). Combining its mass and radius yields a mean bulk density of 53.24 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 28.38 g⊕ (278.31 m/s²), and an escape velocity of 102.2 km/s.
In its orbital architecture around Kepler-58, Kepler-58 d completes one full revolution every 40.101 Earth days at a semi-major axis of 0.236 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 64 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 583 K (+310°C / +590°F) and receiving 18.24 S⊕ (~24,830 W/m²), Kepler-58 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-58 is classified as a stellar host with an effective photospheric temperature of 6,099 K, a radius of 1.127 R☉, a mass of 1.024 M☉, an estimated bolometric luminosity of 1.577 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.14 Gyr and a metallicity of [Fe/H] = 0.1 dex (metal-rich relative to the Sun). From Earth, Kepler-58 shines at apparent V-band magnitude 15.086 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-58 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-58 d sharing its stellar neighborhood alongside Kepler-58 e, Kepler-58 b, Kepler-58 c.
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-58 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,099 K |
| Stellar Radius | 1.1270 R☉ |
| Stellar Mass | 1.0240 M☉ |
| Bolometric Luminosity | 1.577 L☉ |
| Metallicity [Fe/H] | 0.100 dex |
| Stellar Age | 2.140 Gyr |
| Apparent Magnitude | V: 15.086 · G: 14.866 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.236000 AU |
| Orbital Period | 40.101 days |
| Mean Orbital Velocity | 64 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.4400° |
| Mean Bulk Density | 53.24 g/cm³ (102.2 km/s vesc) |
| Insolation Flux | 18.2440 S⊕ (~24,830 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3161.300 LY (969.252 pc) |