Kepler-39 b
Astrophysical Synthesis & Habitability Characterization
Kepler-39 b is a confirmed gas giant exoplanet orbiting the star Kepler-39, located approximately 3448.8 light-years (1057.41 parsecs) from the Solar System. First announced in 2011 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.8285% across the stellar disk), this world measures 13.9 Earth radii (1.24 Jupiter radii) and has a measured mass of 6388.1 Earth masses (20.1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 13.12 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 33.06 g⊕ (324.21 m/s²), and an escape velocity of 239.8 km/s.
In its orbital architecture around Kepler-39, Kepler-39 b completes one full revolution every 21.087 Earth days at a semi-major axis of 0.164 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 84.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.112 carries the world between 0.1456 AU at periapsis and 0.1824 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 897 K (+624°C / +1155°F) and receiving 90.22 S⊕ (~122,789 W/m²), Kepler-39 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-39 is classified as a warm F-type star of spectral type F7 V with an effective photospheric temperature of 6,350 K, a radius of 1.4 R☉, a mass of 1.29 M☉, an estimated bolometric luminosity of 2.859 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.1 Gyr and a metallicity of [Fe/H] = 0.1 dex (metal-rich relative to the Sun). From Earth, Kepler-39 shines at apparent V-band magnitude 14.355 (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-39 |
| Spectral Type | F7 V |
| Effective Temp (Teff) | 6,350 K |
| Stellar Radius | 1.4000 R☉ |
| Stellar Mass | 1.2900 M☉ |
| Bolometric Luminosity | 2.859 L☉ |
| Metallicity [Fe/H] | 0.100 dex |
| Stellar Age | 2.100 Gyr |
| Apparent Magnitude | V: 14.355 · G: 14.262 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.164000 AU |
| Orbital Period | 21.087 days |
| Mean Orbital Velocity | 84.6 km/s |
| Orbital Eccentricity (e) | 0.11200 |
| Orbital Inclination (i) | 89.0700° |
| Mean Bulk Density | 13.12 g/cm³ (239.8 km/s vesc) |
| Insolation Flux | 90.2200 S⊕ (~122,789 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3448.800 LY (1057.410 pc) |