Kepler-424 c
Astrophysical Synthesis & Habitability Characterization
Kepler-424 c 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 McDonald Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.7 Earth radii (1.13 Jupiter radii) and has a measured mass of 2215.18 Earth masses (6.97 Jupiter masses). Combining its mass and radius yields a mean bulk density of 5.96 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 13.73 g⊕ (134.65 m/s²), and an escape velocity of 147.7 km/s.
In its orbital architecture around Kepler-424, Kepler-424 c completes one full revolution every 223.3 Earth days at a semi-major axis of 0.73 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 35.6 km/s (compared to Earth's 29.8 km/s).
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.700 R⊕, Kepler-424 c exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
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 c sharing its stellar neighborhood alongside Kepler-424 b.
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: McDonald Observatory · 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) | 0.730000 AU |
| Orbital Period | 223.3 days |
| Mean Orbital Velocity | 35.6 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 5.96 g/cm³ (147.7 km/s vesc) |
| Insolation Flux | 1.3285 S⊕ (~1,808 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2278.700 LY (698.646 pc) |