K2-115 b
Astrophysical Synthesis & Habitability Characterization
K2-115 b is a confirmed gas giant exoplanet orbiting the star K2-115, located approximately 1349 light-years (413.59 parsecs) from the Solar System. First announced in 2017 by K2 using the Transit detection technique (producing an estimated primary transit depth of 1.6017% across the stellar disk), this world measures 11.803 Earth radii (1.05 Jupiter radii) and has a measured mass of 321.007 Earth masses (1.01 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.08 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.3 g⊕ (22.56 m/s²), and an escape velocity of 58.3 km/s.
In its orbital architecture around K2-115, K2-115 b completes one full revolution every 20.273 Earth days at a semi-major axis of 0.1415 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 75.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.063 carries the world between 0.1326 AU at periapsis and 0.1504 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 696 K (+423°C / +793°F) and receiving 20.44 S⊕ (~27,818 W/m²), K2-115 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-115 is classified as a solar-type yellow star of spectral type G4 with an effective photospheric temperature of 5,870 K, a radius of 0.855 R☉, a mass of 0.918 M☉, an estimated bolometric luminosity of 0.779 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.2 Gyr and a metallicity of [Fe/H] = -0.198 dex (metal-poor relative to the Sun). From Earth, K2-115 shines at apparent V-band magnitude 13.444 (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: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | K2-115 |
| Spectral Type | G4 |
| Effective Temp (Teff) | 5,870 K |
| Stellar Radius | 0.8550 R☉ |
| Stellar Mass | 0.9180 M☉ |
| Bolometric Luminosity | 0.779 L☉ |
| Metallicity [Fe/H] | -0.198 dex |
| Stellar Age | 2.200 Gyr |
| Apparent Magnitude | V: 13.444 · G: 13.200 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.141500 AU |
| Orbital Period | 20.273 days |
| Mean Orbital Velocity | 75.9 km/s |
| Orbital Eccentricity (e) | 0.06300 |
| Orbital Inclination (i) | 88.9120° |
| Mean Bulk Density | 1.08 g/cm³ (58.3 km/s vesc) |
| Insolation Flux | 20.4393 S⊕ (~27,818 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1349.000 LY (413.591 pc) |