Kepler-339 d
Astrophysical Synthesis & Habitability Characterization
Kepler-339 d is a confirmed terrestrial exoplanet orbiting the star Kepler-339, located approximately 2011.2 light-years (616.64 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0179% across the stellar disk), this world measures 1.17 Earth radii and has a measured mass of 14.7 Earth masses. Combining its mass and radius yields a mean bulk density of 50.61 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 10.74 g⊕ (105.32 m/s²), and an escape velocity of 39.6 km/s.
In its orbital architecture around Kepler-339, Kepler-339 d completes one full revolution every 10.558 Earth days at a semi-major axis of 0.091 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 93.8 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 796 K (+523°C / +973°F) and receiving 58.65 S⊕ (~79,824 W/m²), Kepler-339 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-339 is classified as a stellar host with an effective photospheric temperature of 5,631 K, a radius of 0.802 R☉, a mass of 0.87 M☉, an estimated bolometric luminosity of 0.58 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.98 Gyr and a metallicity of [Fe/H] = 0.033 dex (near-solar heavy-element abundance). From Earth, Kepler-339 shines at apparent V-band magnitude 14.706 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-339 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-339 d sharing its stellar neighborhood alongside Kepler-339 b, Kepler-339 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-339 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,631 K |
| Stellar Radius | 0.8020 R☉ |
| Stellar Mass | 0.8700 M☉ |
| Bolometric Luminosity | 0.58 L☉ |
| Metallicity [Fe/H] | 0.033 dex |
| Stellar Age | 0.980 Gyr |
| Apparent Magnitude | V: 14.706 · G: 14.513 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.091000 AU |
| Orbital Period | 10.558 days |
| Mean Orbital Velocity | 93.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.2300° |
| Mean Bulk Density | 50.61 g/cm³ (39.6 km/s vesc) |
| Insolation Flux | 58.6510 S⊕ (~79,824 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2011.200 LY (616.637 pc) |