Kepler-643 b
Astrophysical Synthesis & Habitability Characterization
Kepler-643 b is a confirmed gas giant exoplanet orbiting the star Kepler-643, located approximately 3468.9 light-years (1063.58 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1366% across the stellar disk), this world measures 10.16 Earth radii (0.91 Jupiter radii) and has a measured mass of 321.008 Earth masses (1.01 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.69 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.11 g⊕ (30.5 m/s²), and an escape velocity of 62.9 km/s.
In its orbital architecture around Kepler-643, Kepler-643 b completes one full revolution every 16.339 Earth days at a semi-major axis of 0.13485 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 89.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.37, swinging from 0.085 AU at periapsis out to 0.1847 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 963 K (+690°C / +1274°F) and receiving 211.71 S⊕ (~288,139 W/m²), Kepler-643 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-643 is classified as a stellar host with an effective photospheric temperature of 4,908 K, a radius of 2.52 R☉, a mass of 1 M☉, an estimated bolometric luminosity of 3.306 L☉. Stellar evolution modeling indicates an estimated stellar age of 12.02 Gyr and a metallicity of [Fe/H] = 0.13 dex (metal-rich relative to the Sun). From Earth, Kepler-643 shines at apparent V-band magnitude 13.988 (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-643 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,908 K |
| Stellar Radius | 2.5200 R☉ |
| Stellar Mass | 1.0000 M☉ |
| Bolometric Luminosity | 3.306 L☉ |
| Metallicity [Fe/H] | 0.130 dex |
| Stellar Age | 12.020 Gyr |
| Apparent Magnitude | V: 13.988 · G: 13.769 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.134850 AU |
| Orbital Period | 16.339 days |
| Mean Orbital Velocity | 89.8 km/s |
| Orbital Eccentricity (e) | 0.37000 |
| Orbital Inclination (i) | 88.9100° |
| Mean Bulk Density | 1.69 g/cm³ (62.9 km/s vesc) |
| Insolation Flux | 211.7110 S⊕ (~288,139 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3468.900 LY (1063.580 pc) |