Kepler-1864 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1864 b is a confirmed sub-earth exoplanet orbiting the star Kepler-1864, located approximately 974.9 light-years (298.89 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.005% across the stellar disk), this world measures 0.754 Earth radii and has a measured mass of 0.353 Earth masses. Combining its mass and radius yields a mean bulk density of 4.54 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.62 g⊕ (6.08 m/s²), and an escape velocity of 7.7 km/s.
In its orbital architecture around Kepler-1864, Kepler-1864 b completes one full revolution every 3.882 Earth days at a semi-major axis of 0.049 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 137.3 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 1156 K (+883°C / +1621°F) and receiving 427.60 S⊕ (~581,964 W/m²), Kepler-1864 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1864 is classified as a stellar host with an effective photospheric temperature of 5,854 K, a radius of 0.979 R☉, a mass of 1.03 M☉, an estimated bolometric luminosity of 1.01 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.62 Gyr and a metallicity of [Fe/H] = 0.06 dex (metal-rich relative to the Sun). From Earth, Kepler-1864 shines at apparent V-band magnitude 12.123 (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-1864 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,854 K |
| Stellar Radius | 0.9790 R☉ |
| Stellar Mass | 1.0300 M☉ |
| Bolometric Luminosity | 1.01 L☉ |
| Metallicity [Fe/H] | 0.060 dex |
| Stellar Age | 1.620 Gyr |
| Apparent Magnitude | V: 12.123 · G: 12.037 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.049000 AU |
| Orbital Period | 3.882 days |
| Mean Orbital Velocity | 137.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.6600° |
| Mean Bulk Density | 4.54 g/cm³ (7.7 km/s vesc) |
| Insolation Flux | 427.6000 S⊕ (~581,964 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 974.900 LY (298.894 pc) |