KIC 8121913 b
Astrophysical Synthesis & Habitability Characterization
KIC 8121913 b is a confirmed gas giant exoplanet orbiting the star KIC 8121913, located approximately 2306.9 light-years (707.3 parsecs) from the Solar System. First announced in 2021 by Kepler using the Orbital Brightness Modulation detection technique, this world measures 13.4 Earth radii (1.2 Jupiter radii) and has a measured mass of 667.44 Earth masses (2.1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.53 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.72 g⊕ (36.48 m/s²), and an escape velocity of 78.9 km/s.
In its orbital architecture around KIC 8121913, KIC 8121913 b completes one full revolution every 3.295 Earth days.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.400 R⊕, KIC 8121913 b 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 KIC 8121913 is classified as a stellar host with an effective photospheric temperature of 5,975 K, a radius of 2.233 R☉, a mass of 1.456 M☉, an estimated bolometric luminosity of 5.702 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.252 dex (metal-rich relative to the Sun). From Earth, KIC 8121913 shines at apparent V-band magnitude 12.38 (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 | KIC 8121913 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,975 K |
| Stellar Radius | 2.2330 R☉ |
| Stellar Mass | 1.4560 M☉ |
| Bolometric Luminosity | 5.702 L☉ |
| Metallicity [Fe/H] | 0.252 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.380 · G: 12.303 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 3.295 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.53 g/cm³ (78.9 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2306.900 LY (707.303 pc) |