Kepler-448 c
Astrophysical Synthesis & Habitability Characterization
Kepler-448 c is a confirmed gas giant exoplanet orbiting the star KOI-12, located approximately 1302.7 light-years (399.4 parsecs) from the Solar System. First announced in 2017 by Kepler using the Transit Timing Variations detection technique (producing an estimated primary transit depth of 0.6175% across the stellar disk), this world measures 12 Earth radii (1.07 Jupiter radii) and has a measured mass of 6992.26 Earth masses (22 Jupiter masses). Combining its mass and radius yields a mean bulk density of 22.31 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 48.56 g⊕ (476.21 m/s²), and an escape velocity of 270 km/s.
In its orbital architecture around KOI-12, Kepler-448 c completes one full revolution every 2500 Earth days (6.84Julian years) at a semi-major axis of 4.2 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 18.3 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.65, swinging from 1.47 AU at periapsis out to 6.93 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.000 R⊕, Kepler-448 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 KOI-12 is classified as a stellar host with an effective photospheric temperature of 6,635 K, a radius of 1.4 R☉, a mass of 1.5 M☉, an estimated bolometric luminosity of 3.408 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.45 Gyr and a metallicity of [Fe/H] = 0.082 dex (metal-rich relative to the Sun). From Earth, KOI-12 shines at apparent V-band magnitude 11.51 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The KOI-12 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-448 c sharing its stellar neighborhood alongside KOI-12 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: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | KOI-12 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,635 K |
| Stellar Radius | 1.4000 R☉ |
| Stellar Mass | 1.5000 M☉ |
| Bolometric Luminosity | 3.408 L☉ |
| Metallicity [Fe/H] | 0.082 dex |
| Stellar Age | 1.450 Gyr |
| Apparent Magnitude | V: 11.510 · G: 11.254 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 4.200000 AU |
| Orbital Period | 2500 days |
| Mean Orbital Velocity | 18.3 km/s |
| Orbital Eccentricity (e) | 0.65000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 22.31 g/cm³ (270 km/s vesc) |
| Insolation Flux | 0.2399 S⊕ (~327 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1302.700 LY (399.398 pc) |