KOI-13 b
Astrophysical Synthesis & Habitability Characterization
KOI-13 b is a confirmed gas giant exoplanet orbiting the star KOI-13, located approximately 1693.1 light-years (519.1 parsecs) from the Solar System. First announced in 2011 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.7974% across the stellar disk), this world measures 16.948 Earth radii (1.51 Jupiter radii) and has a measured mass of 2949.462 Earth masses (9.28 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.34 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 10.27 g⊕ (100.71 m/s²), and an escape velocity of 147.6 km/s.
In its orbital architecture around KOI-13, KOI-13 b completes one full revolution every 1.764 Earth days at a semi-major axis of 0.03641 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 224.6 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.00064 (ranging from 0.0364 AU at periapsis to 0.0364 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 2550 K (+2277°C / +4131°F) and receiving 25,339.90 S⊕ (~34,487,605 W/m²), KOI-13 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star KOI-13 is classified as a stellar host with an effective photospheric temperature of 7,650 K, a radius of 1.74 R☉, a mass of 1.72 M☉, an estimated bolometric luminosity of 9.303 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.12 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, KOI-13 shines at apparent V-band magnitude 9.791 (accessible to binoculars and small amateur telescopes) 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 | KOI-13 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 7,650 K |
| Stellar Radius | 1.7400 R☉ |
| Stellar Mass | 1.7200 M☉ |
| Bolometric Luminosity | 9.303 L☉ |
| Metallicity [Fe/H] | 0.200 dex |
| Stellar Age | 1.120 Gyr |
| Apparent Magnitude | V: 9.791 · G: 10.368 |
| System Architecture | 3 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.036410 AU |
| Orbital Period | 1.764 days |
| Mean Orbital Velocity | 224.6 km/s |
| Orbital Eccentricity (e) | 0.00064 |
| Orbital Inclination (i) | 86.7700° |
| Mean Bulk Density | 3.34 g/cm³ (147.6 km/s vesc) |
| Insolation Flux | 25339.9010 S⊕ (~34,487,605 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1693.100 LY (519.096 pc) |