KOI-12 b
Astrophysical Synthesis & Habitability Characterization
KOI-12 b 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 2015 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.8151% across the stellar disk), this world measures 13.787 Earth radii (1.23 Jupiter radii) and has a measured mass of 349.613 Earth masses (1.1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.74 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.84 g⊕ (18.04 m/s²), and an escape velocity of 56.3 km/s.
In its orbital architecture around KOI-12, KOI-12 b completes one full revolution every 17.855 Earth days at a semi-major axis of 0.154 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 93.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.34, swinging from 0.1016 AU at periapsis out to 0.2064 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 911 K (+638°C / +1180°F) and receiving 196.51 S⊕ (~267,446 W/m²), KOI-12 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
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 KOI-12 b sharing its stellar neighborhood alongside Kepler-448 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 | 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) | 0.154000 AU |
| Orbital Period | 17.855 days |
| Mean Orbital Velocity | 93.8 km/s |
| Orbital Eccentricity (e) | 0.34000 |
| Orbital Inclination (i) | 88.9500° |
| Mean Bulk Density | 0.74 g/cm³ (56.3 km/s vesc) |
| Insolation Flux | 196.5070 S⊕ (~267,446 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1302.700 LY (399.398 pc) |