Kepler-804 c
Astrophysical Synthesis & Habitability Characterization
Kepler-804 c is a confirmed terrestrial exoplanet orbiting the star Kepler-804, located approximately 2118.9 light-years (649.65 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0099% across the stellar disk), this world measures 1.14 Earth radii and has a measured mass of 1.55 Earth masses. Combining its mass and radius yields a mean bulk density of 5.77 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.19 g⊕ (11.67 m/s²), and an escape velocity of 13 km/s.
In its orbital architecture around Kepler-804, Kepler-804 c completes one full revolution every 9.652 Earth days at a semi-major axis of 0.08654 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 97.5 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 890 K (+617°C / +1143°F) and receiving 141.84 S⊕ (~193,043 W/m²), Kepler-804 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-804 is classified as a stellar host with an effective photospheric temperature of 5,817 K, a radius of 1.05 R☉, a mass of 1.01 M☉, an estimated bolometric luminosity of 1.133 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.25 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-804 shines at apparent V-band magnitude 13.864 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-804 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-804 c sharing its stellar neighborhood alongside Kepler-804 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-804 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,817 K |
| Stellar Radius | 1.0500 R☉ |
| Stellar Mass | 1.0100 M☉ |
| Bolometric Luminosity | 1.133 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 5.250 Gyr |
| Apparent Magnitude | V: 13.864 · G: 13.736 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.086540 AU |
| Orbital Period | 9.652 days |
| Mean Orbital Velocity | 97.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5900° |
| Mean Bulk Density | 5.77 g/cm³ (13 km/s vesc) |
| Insolation Flux | 141.8390 S⊕ (~193,043 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2118.900 LY (649.650 pc) |