Kepler-15 b
Astrophysical Synthesis & Habitability Characterization
Kepler-15 b is a confirmed gas giant exoplanet orbiting the star Kepler-15, located approximately 2411.6 light-years (739.41 parsecs) from the Solar System. First announced in 2011 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.9889% across the stellar disk), this world measures 10.76 Earth radii (0.96 Jupiter radii) and has a measured mass of 209.76 Earth masses (0.66 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.93 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.81 g⊕ (17.75 m/s²), and an escape velocity of 49.4 km/s.
In its orbital architecture around Kepler-15, Kepler-15 b completes one full revolution every 4.943 Earth days at a semi-major axis of 0.05714 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 125.8 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.06 carries the world between 0.0537 AU at periapsis and 0.0606 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1251 K (+978°C / +1792°F) and receiving 430.68 S⊕ (~586,151 W/m²), Kepler-15 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-15 is classified as a stellar host with an effective photospheric temperature of 5,515 K, a radius of 0.992 R☉, a mass of 1.018 M☉, an estimated bolometric luminosity of 0.817 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.7 Gyr and a metallicity of [Fe/H] = 0.36 dex (metal-rich relative to the Sun). From Earth, Kepler-15 shines at apparent V-band magnitude 13.81 (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-15 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,515 K |
| Stellar Radius | 0.9920 R☉ |
| Stellar Mass | 1.0180 M☉ |
| Bolometric Luminosity | 0.817 L☉ |
| Metallicity [Fe/H] | 0.360 dex |
| Stellar Age | 3.700 Gyr |
| Apparent Magnitude | V: 13.810 · G: 13.714 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.057140 AU |
| Orbital Period | 4.943 days |
| Mean Orbital Velocity | 125.8 km/s |
| Orbital Eccentricity (e) | 0.06000 |
| Orbital Inclination (i) | 87.4400° |
| Mean Bulk Density | 0.93 g/cm³ (49.4 km/s vesc) |
| Insolation Flux | 430.6770 S⊕ (~586,151 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2411.600 LY (739.412 pc) |