Kepler-340 c
Astrophysical Synthesis & Habitability Characterization
Kepler-340 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-340, located approximately 2637.8 light-years (808.76 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0279% across the stellar disk), this world measures 3.37 Earth radii (0.3 Jupiter radii) and has a measured mass of 11.3 Earth masses. Combining its mass and radius yields a mean bulk density of 1.63 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.99 g⊕ (9.71 m/s²), and an escape velocity of 20.5 km/s.
In its orbital architecture around Kepler-340, Kepler-340 c completes one full revolution every 22.825 Earth days at a semi-major axis of 0.178 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 84.8 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 946 K (+673°C / +1243°F) and receiving 154.65 S⊕ (~210,483 W/m²), Kepler-340 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-340 is classified as a stellar host with an effective photospheric temperature of 6,620 K, a radius of 1.85 R☉, a mass of 1.65 M☉, an estimated bolometric luminosity of 5.897 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.29 Gyr and a metallicity of [Fe/H] = 0.06 dex (metal-rich relative to the Sun). From Earth, Kepler-340 shines at apparent V-band magnitude 12.329 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-340 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-340 c sharing its stellar neighborhood alongside Kepler-340 b.
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 | Kepler-340 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,620 K |
| Stellar Radius | 1.8500 R☉ |
| Stellar Mass | 1.6500 M☉ |
| Bolometric Luminosity | 5.897 L☉ |
| Metallicity [Fe/H] | 0.060 dex |
| Stellar Age | 1.290 Gyr |
| Apparent Magnitude | V: 12.329 · G: 12.303 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.178000 AU |
| Orbital Period | 22.825 days |
| Mean Orbital Velocity | 84.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.3800° |
| Mean Bulk Density | 1.63 g/cm³ (20.5 km/s vesc) |
| Insolation Flux | 154.6530 S⊕ (~210,483 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2637.800 LY (808.762 pc) |