Kepler-423 b
Astrophysical Synthesis & Habitability Characterization
Kepler-423 b is a confirmed gas giant exoplanet orbiting the star Kepler-423, located approximately 2474.7 light-years (758.75 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 1.6625% across the stellar disk), this world measures 13.361 Earth radii (1.19 Jupiter radii) and has a measured mass of 189.101 Earth masses (0.59 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.44 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.06 g⊕ (10.4 m/s²), and an escape velocity of 42.1 km/s.
In its orbital architecture around Kepler-423, Kepler-423 b completes one full revolution every 2.684 Earth days at a semi-major axis of 0.03585 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 145.3 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.019 (ranging from 0.0352 AU at periapsis to 0.0365 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1605 K (+1332°C / +2430°F) and receiving 649.15 S⊕ (~883,490 W/m²), Kepler-423 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-423 is classified as a solar-type yellow star of spectral type G4 V with an effective photospheric temperature of 5,560 K, a radius of 0.95 R☉, a mass of 0.85 M☉, an estimated bolometric luminosity of 0.774 L☉. Stellar evolution modeling indicates an estimated stellar age of 11 Gyr and a metallicity of [Fe/H] = -0.1 dex (near-solar heavy-element abundance). From Earth, Kepler-423 shines at apparent V-band magnitude 14.462 (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-423 |
| Spectral Type | G4 V |
| Effective Temp (Teff) | 5,560 K |
| Stellar Radius | 0.9500 R☉ |
| Stellar Mass | 0.8500 M☉ |
| Bolometric Luminosity | 0.774 L☉ |
| Metallicity [Fe/H] | -0.100 dex |
| Stellar Age | 11.000 Gyr |
| Apparent Magnitude | V: 14.462 · G: 14.280 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.035850 AU |
| Orbital Period | 2.684 days |
| Mean Orbital Velocity | 145.3 km/s |
| Orbital Eccentricity (e) | 0.01900 |
| Orbital Inclination (i) | 87.8280° |
| Mean Bulk Density | 0.44 g/cm³ (42.1 km/s vesc) |
| Insolation Flux | 649.1480 S⊕ (~883,490 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2474.700 LY (758.753 pc) |