Kepler-300 c
Astrophysical Synthesis & Habitability Characterization
Kepler-300 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-300, located approximately 3582.7 light-years (1098.45 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0525% across the stellar disk), this world measures 2.25 Earth radii and has a measured mass of 5.69 Earth masses. Combining its mass and radius yields a mean bulk density of 2.75 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.8 km/s.
In its orbital architecture around Kepler-300, Kepler-300 c completes one full revolution every 40.715 Earth days at a semi-major axis of 0.232 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 62 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 516 K (+243°C / +469°F) and receiving 43.25 S⊕ (~58,861 W/m²), Kepler-300 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-300 is classified as a stellar host with an effective photospheric temperature of 5,986 K, a radius of 0.9 R☉, a mass of 1.07 M☉, an estimated bolometric luminosity of 0.933 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.63 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, Kepler-300 shines at apparent V-band magnitude 14.25 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-300 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-300 c sharing its stellar neighborhood alongside Kepler-300 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-300 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,986 K |
| Stellar Radius | 0.9000 R☉ |
| Stellar Mass | 1.0700 M☉ |
| Bolometric Luminosity | 0.933 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 3.630 Gyr |
| Apparent Magnitude | V: 14.250 · G: 14.180 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.232000 AU |
| Orbital Period | 40.715 days |
| Mean Orbital Velocity | 62 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.7400° |
| Mean Bulk Density | 2.75 g/cm³ (17.8 km/s vesc) |
| Insolation Flux | 43.2480 S⊕ (~58,861 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3582.700 LY (1098.450 pc) |