Kepler-338 e
Astrophysical Synthesis & Habitability Characterization
Kepler-338 e is a confirmed super-earth exoplanet orbiting the star Kepler-338, located approximately 1803 light-years (552.8 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0068% across the stellar disk), this world measures 1.56 Earth radii and has a measured mass of 8.5 Earth masses. Combining its mass and radius yields a mean bulk density of 12.35 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 3.49 g⊕ (34.23 m/s²), and an escape velocity of 26.1 km/s.
In its orbital architecture around Kepler-338, Kepler-338 e completes one full revolution every 9.341 Earth days at a semi-major axis of 0.08979 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 104.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.05 carries the world between 0.0853 AU at periapsis and 0.0943 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1143 K (+870°C / +1598°F) and receiving 428.52 S⊕ (~583,221 W/m²), Kepler-338 e orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-338 is classified as a stellar host with an effective photospheric temperature of 5,999 K, a radius of 1.735 R☉, a mass of 1.14 M☉, an estimated bolometric luminosity of 3.498 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.46 Gyr and a metallicity of [Fe/H] = -0.029 dex (near-solar heavy-element abundance). From Earth, Kepler-338 shines at apparent V-band magnitude 12.19 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-338 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-338 e sharing its stellar neighborhood alongside Kepler-338 b, Kepler-338 c, Kepler-338 d.
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-338 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,999 K |
| Stellar Radius | 1.7350 R☉ |
| Stellar Mass | 1.1400 M☉ |
| Bolometric Luminosity | 3.498 L☉ |
| Metallicity [Fe/H] | -0.029 dex |
| Stellar Age | 6.460 Gyr |
| Apparent Magnitude | V: 12.190 · G: 12.083 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.089790 AU |
| Orbital Period | 9.341 days |
| Mean Orbital Velocity | 104.6 km/s |
| Orbital Eccentricity (e) | 0.05000 |
| Orbital Inclination (i) | 87.4900° |
| Mean Bulk Density | 12.35 g/cm³ (26.1 km/s vesc) |
| Insolation Flux | 428.5240 S⊕ (~583,221 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1803.000 LY (552.798 pc) |