Kepler-1339 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1339 b is a confirmed sub-earth exoplanet orbiting the star Kepler-1339, located approximately 1210.2 light-years (371.05 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0049% across the stellar disk), this world measures 0.71 Earth radii and has a measured mass of 0.285 Earth masses. Combining its mass and radius yields a mean bulk density of 4.39 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.57 g⊕ (5.59 m/s²), and an escape velocity of 7.1 km/s.
In its orbital architecture around Kepler-1339, Kepler-1339 b completes one full revolution every 1.342 Earth days at a semi-major axis of 0.02356 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 191.1 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 1642 K (+1369°C / +2496°F) and receiving 3,094.82 S⊕ (~4,212,046 W/m²), Kepler-1339 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1339 is classified as a stellar host with an effective photospheric temperature of 5,586 K, a radius of 0.93 R☉, a mass of 0.94 M☉, an estimated bolometric luminosity of 0.756 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.62 Gyr and a metallicity of [Fe/H] = 0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-1339 shines at apparent V-band magnitude 12.344 (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-1339 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,586 K |
| Stellar Radius | 0.9300 R☉ |
| Stellar Mass | 0.9400 M☉ |
| Bolometric Luminosity | 0.756 L☉ |
| Metallicity [Fe/H] | 0.010 dex |
| Stellar Age | 5.620 Gyr |
| Apparent Magnitude | V: 12.344 · G: 12.124 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.023560 AU |
| Orbital Period | 1.342 days |
| Mean Orbital Velocity | 191.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.5600° |
| Mean Bulk Density | 4.39 g/cm³ (7.1 km/s vesc) |
| Insolation Flux | 3094.8170 S⊕ (~4,212,046 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1210.200 LY (371.049 pc) |