Kepler-158 d
Astrophysical Synthesis & Habitability Characterization
Kepler-158 d is a confirmed sub-earth exoplanet orbiting the star Kepler-158, located approximately 1028 light-years (315.18 parsecs) from the Solar System. First announced in 2024 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0035% across the stellar disk), this world measures 0.43 Earth radii and has a measured mass of 0.047 Earth masses. Combining its mass and radius yields a mean bulk density of 3.26 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 0.25 g⊕ (2.45 m/s²), and an escape velocity of 3.7 km/s.
In its orbital architecture around Kepler-158, Kepler-158 d completes one full revolution every 0.645 Earth days.
ℹ️ Thermal & Atmospheric Regime: Current photometric and spectroscopic constraints for Kepler-158 d place it outside the conservative habitable zone definition pending further atmospheric characterization.
The host star Kepler-158 is classified as an orange K-type star of spectral type K with an effective photospheric temperature of 4,896 K, a radius of 0.668 R☉, a mass of 0.656 M☉, an estimated bolometric luminosity of 0.23 L☉. Stellar evolution modeling indicates an estimated stellar age of 13.9 Gyr and a metallicity of [Fe/H] = -0.3 dex (metal-poor relative to the Sun). From Earth, Kepler-158 shines at apparent V-band magnitude 14.743 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-158 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-158 d sharing its stellar neighborhood alongside Kepler-158 b, Kepler-158 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-158 |
| Spectral Type | K |
| Effective Temp (Teff) | 4,896 K |
| Stellar Radius | 0.6680 R☉ |
| Stellar Mass | 0.6560 M☉ |
| Bolometric Luminosity | 0.23 L☉ |
| Metallicity [Fe/H] | -0.300 dex |
| Stellar Age | 13.900 Gyr |
| Apparent Magnitude | V: 14.743 · G: 14.417 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 0.645 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 3.26 g/cm³ (3.7 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1028.000 LY (315.177 pc) |