Kepler-84 c
Astrophysical Synthesis & Habitability Characterization
Kepler-84 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-84, located approximately 3339.5 light-years (1023.9 parsecs) from the Solar System. First announced in 2012 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0229% across the stellar disk), this world measures 2.36 Earth radii and has a measured mass of 20.2 Earth masses. Combining its mass and radius yields a mean bulk density of 8.47 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 3.63 g⊕ (35.6 m/s²), and an escape velocity of 32.7 km/s.
In its orbital architecture around Kepler-84, Kepler-84 c completes one full revolution every 12.883 Earth days at a semi-major axis of 0.1072 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 90.5 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 865 K (+592°C / +1098°F) and receiving 132.23 S⊕ (~179,965 W/m²), Kepler-84 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-84 is classified as a stellar host with an effective photospheric temperature of 6,039 K, a radius of 1.43 R☉, a mass of 1 M☉, an estimated bolometric luminosity of 2.44 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.98 Gyr and a metallicity of [Fe/H] = -0.07 dex (near-solar heavy-element abundance). From Earth, Kepler-84 shines at apparent V-band magnitude 14.92 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-84 system is a multi-planet architecture hosting 5 confirmed worlds, with Kepler-84 c sharing its stellar neighborhood alongside Kepler-84 d, Kepler-84 b, Kepler-84 e, Kepler-84 f.
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-84 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,039 K |
| Stellar Radius | 1.4300 R☉ |
| Stellar Mass | 1.0000 M☉ |
| Bolometric Luminosity | 2.44 L☉ |
| Metallicity [Fe/H] | -0.070 dex |
| Stellar Age | 3.980 Gyr |
| Apparent Magnitude | V: 14.920 · G: 14.790 |
| System Architecture | 1 Star, 5 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.107200 AU |
| Orbital Period | 12.883 days |
| Mean Orbital Velocity | 90.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 81.1300° |
| Mean Bulk Density | 8.47 g/cm³ (32.7 km/s vesc) |
| Insolation Flux | 132.2300 S⊕ (~179,965 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3339.500 LY (1023.900 pc) |