Kepler-424 b
Astrophysical Synthesis & Habitability Characterization
Kepler-424 b is a confirmed gas giant exoplanet orbiting the star Kepler-424, located approximately 2278.7 light-years (698.65 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.9474% across the stellar disk), this world measures 9.98 Earth radii (0.89 Jupiter radii) and has a measured mass of 327.35 Earth masses (1.03 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.82 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.29 g⊕ (32.26 m/s²), and an escape velocity of 64.1 km/s.
In its orbital architecture around Kepler-424, Kepler-424 b completes one full revolution every 3.312 Earth days at a semi-major axis of 0.044 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 144.5 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 1116 K (+843°C / +1549°F) and receiving 470.75 S⊕ (~640,696 W/m²), Kepler-424 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-424 is classified as a stellar host with an effective photospheric temperature of 5,460 K, a radius of 0.94 R☉, a mass of 1.01 M☉, an estimated bolometric luminosity of 0.705 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.9 Gyr and a metallicity of [Fe/H] = 0.44 dex (metal-rich relative to the Sun). From Earth, Kepler-424 shines at apparent V-band magnitude 14.429 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-424 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-424 b sharing its stellar neighborhood alongside Kepler-424 c.
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-424 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,460 K |
| Stellar Radius | 0.9400 R☉ |
| Stellar Mass | 1.0100 M☉ |
| Bolometric Luminosity | 0.705 L☉ |
| Metallicity [Fe/H] | 0.440 dex |
| Stellar Age | 4.900 Gyr |
| Apparent Magnitude | V: 14.429 · G: 14.229 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.044000 AU |
| Orbital Period | 3.312 days |
| Mean Orbital Velocity | 144.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 84.6800° |
| Mean Bulk Density | 1.82 g/cm³ (64.1 km/s vesc) |
| Insolation Flux | 470.7540 S⊕ (~640,696 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2278.700 LY (698.646 pc) |