Kepler-888 b
Astrophysical Synthesis & Habitability Characterization
Kepler-888 b is a confirmed super-earth exoplanet orbiting the star Kepler-888, located approximately 1372.5 light-years (420.82 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0321% across the stellar disk), this world measures 1.76 Earth radii and has a measured mass of 3.75 Earth masses. Combining its mass and radius yields a mean bulk density of 3.79 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.21 g⊕ (11.87 m/s²), and an escape velocity of 16.3 km/s.
In its orbital architecture around Kepler-888, Kepler-888 b completes one full revolution every 70.698 Earth days at a semi-major axis of 0.31481 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 48.4 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 417 K (+144°C / +291°F) and receiving 7.85 S⊕ (~10,689 W/m²), Kepler-888 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-888 is classified as a stellar host with an effective photospheric temperature of 5,875 K, a radius of 0.9 R☉, a mass of 0.97 M☉, an estimated bolometric luminosity of 0.866 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.48 Gyr and a metallicity of [Fe/H] = -0.21 dex (metal-poor relative to the Sun). From Earth, Kepler-888 shines at apparent V-band magnitude 13.061 (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-888 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,875 K |
| Stellar Radius | 0.9000 R☉ |
| Stellar Mass | 0.9700 M☉ |
| Bolometric Luminosity | 0.866 L☉ |
| Metallicity [Fe/H] | -0.210 dex |
| Stellar Age | 1.480 Gyr |
| Apparent Magnitude | V: 13.061 · G: 12.981 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.314810 AU |
| Orbital Period | 70.698 days |
| Mean Orbital Velocity | 48.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9800° |
| Mean Bulk Density | 3.79 g/cm³ (16.3 km/s vesc) |
| Insolation Flux | 7.8540 S⊕ (~10,689 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1372.500 LY (420.817 pc) |