Kepler-1802 c
Astrophysical Synthesis & Habitability Characterization
Kepler-1802 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-1802, located approximately 2076.6 light-years (636.69 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1117% across the stellar disk), this world measures 2.322 Earth radii and has a measured mass of 6 Earth masses. Combining its mass and radius yields a mean bulk density of 2.64 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.11 g⊕ (10.89 m/s²), and an escape velocity of 18 km/s.
In its orbital architecture around Kepler-1802, Kepler-1802 c completes one full revolution every 33.136 Earth days at a semi-major axis of 0.1748 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 57.4 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 357 K (+84°C / +183°F) and receiving 3.86 S⊕ (~5,253 W/m²), Kepler-1802 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1802 is classified as a stellar host with an effective photospheric temperature of 4,245 K, a radius of 0.637 R☉, a mass of 0.649 M☉, an estimated bolometric luminosity of 0.118 L☉. Stellar evolution modeling indicates an estimated stellar age of 13.9 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-1802 shines at apparent V-band magnitude 15.905 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-1802 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-1802 c sharing its stellar neighborhood alongside Kepler-1802 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-1802 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,245 K |
| Stellar Radius | 0.6370 R☉ |
| Stellar Mass | 0.6490 M☉ |
| Bolometric Luminosity | 0.118 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 13.900 Gyr |
| Apparent Magnitude | V: 15.905 · G: 16.505 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.174800 AU |
| Orbital Period | 33.136 days |
| Mean Orbital Velocity | 57.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.8700° |
| Mean Bulk Density | 2.64 g/cm³ (18 km/s vesc) |
| Insolation Flux | 3.8600 S⊕ (~5,253 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2076.600 LY (636.694 pc) |