Kepler-433 b
Astrophysical Synthesis & Habitability Characterization
Kepler-433 b is a confirmed gas giant exoplanet orbiting the star Kepler-433, located approximately 6126.2 light-years (1878.31 parsecs) from the Solar System. First announced in 2015 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.4345% across the stellar disk), this world measures 16.25 Earth radii (1.45 Jupiter radii) and has a measured mass of 896.24 Earth masses (2.82 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.15 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.39 g⊕ (33.24 m/s²), and an escape velocity of 83.1 km/s.
In its orbital architecture around Kepler-433, Kepler-433 b completes one full revolution every 5.334 Earth days at a semi-major axis of 0.0679 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 138.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.119 carries the world between 0.0598 AU at periapsis and 0.076 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1776 K (+1503°C / +2737°F) and receiving 1,682.66 S⊕ (~2,290,100 W/m²), Kepler-433 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-433 is classified as a stellar host with an effective photospheric temperature of 6,360 K, a radius of 2.26 R☉, a mass of 1.46 M☉, an estimated bolometric luminosity of 7.498 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.67 Gyr and a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-433 shines at apparent V-band magnitude 14.717 (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-433 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,360 K |
| Stellar Radius | 2.2600 R☉ |
| Stellar Mass | 1.4600 M☉ |
| Bolometric Luminosity | 7.498 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | 2.670 Gyr |
| Apparent Magnitude | V: 14.717 · G: 14.416 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.067900 AU |
| Orbital Period | 5.334 days |
| Mean Orbital Velocity | 138.5 km/s |
| Orbital Eccentricity (e) | 0.11900 |
| Orbital Inclination (i) | 89.2100° |
| Mean Bulk Density | 1.15 g/cm³ (83.1 km/s vesc) |
| Insolation Flux | 1682.6600 S⊕ (~2,290,100 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 6126.200 LY (1878.310 pc) |