KOI-351 g
Astrophysical Synthesis & Habitability Characterization
KOI-351 g is a confirmed gas giant exoplanet orbiting the star KOI-351, located approximately 2766.6 light-years (848.25 parsecs) from the Solar System. First announced in 2013 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.3565% across the stellar disk), this world measures 7.718 Earth radii (0.69 Jupiter radii) and has a measured mass of 15 Earth masses. Combining its mass and radius yields a mean bulk density of 0.18 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.25 g⊕ (2.45 m/s²), and an escape velocity of 15.6 km/s.
In its orbital architecture around KOI-351, KOI-351 g completes one full revolution every 210.735 Earth days at a semi-major axis of 0.71704 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 37 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.0292 (ranging from 0.6961 AU at periapsis to 0.738 AU at apoapsis), the planet experiences minimal orbital distance variation.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 7.718 R⊕, KOI-351 g 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-351 is classified as a stellar host with an effective photospheric temperature of 6,031 K, a radius of 1.185 R☉, a mass of 1.242 M☉, an estimated bolometric luminosity of 1.667 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.53 Gyr and a metallicity of [Fe/H] = 0.083 dex (metal-rich relative to the Sun). From Earth, KOI-351 shines at apparent V-band magnitude 13.883 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The KOI-351 system is a multi-planet architecture hosting 8 confirmed worlds, with KOI-351 g sharing its stellar neighborhood alongside KOI-351 b, KOI-351 c, Kepler-90 i, KOI-351 d, KOI-351 e, KOI-351 f, KOI-351 h.
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-351 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,031 K |
| Stellar Radius | 1.1850 R☉ |
| Stellar Mass | 1.2420 M☉ |
| Bolometric Luminosity | 1.667 L☉ |
| Metallicity [Fe/H] | 0.083 dex |
| Stellar Age | 0.530 Gyr |
| Apparent Magnitude | V: 13.883 · G: 13.740 |
| System Architecture | 1 Star, 8 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.717040 AU |
| Orbital Period | 210.735 days |
| Mean Orbital Velocity | 37 km/s |
| Orbital Eccentricity (e) | 0.02920 |
| Orbital Inclination (i) | 89.9200° |
| Mean Bulk Density | 0.18 g/cm³ (15.6 km/s vesc) |
| Insolation Flux | 3.3870 S⊕ (~4,610 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2766.600 LY (848.254 pc) |