Kepler-1338 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1338 b is a confirmed terrestrial exoplanet orbiting the star Kepler-1338, located approximately 2456.8 light-years (753.26 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0065% across the stellar disk), this world measures 0.92 Earth radii and has a measured mass of 0.721 Earth masses. Combining its mass and radius yields a mean bulk density of 5.11 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.85 g⊕ (8.34 m/s²), and an escape velocity of 9.9 km/s.
In its orbital architecture around Kepler-1338, Kepler-1338 b completes one full revolution every 0.935 Earth days at a semi-major axis of 0.01937 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 225.3 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 2124 K (+1851°C / +3364°F) and receiving 4,712.11 S⊕ (~6,413,183 W/m²), Kepler-1338 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1338 is classified as a stellar host with an effective photospheric temperature of 5,909 K, a radius of 1.05 R☉, a mass of 1.04 M☉, an estimated bolometric luminosity of 1.206 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.8 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-1338 shines at apparent V-band magnitude 13.699 (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-1338 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,909 K |
| Stellar Radius | 1.0500 R☉ |
| Stellar Mass | 1.0400 M☉ |
| Bolometric Luminosity | 1.206 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 3.800 Gyr |
| Apparent Magnitude | V: 13.699 · G: 13.574 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.019370 AU |
| Orbital Period | 0.935 days |
| Mean Orbital Velocity | 225.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.8100° |
| Mean Bulk Density | 5.11 g/cm³ (9.9 km/s vesc) |
| Insolation Flux | 4712.1110 S⊕ (~6,413,183 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2456.800 LY (753.260 pc) |