Kepler-84 d
Astrophysical Synthesis & Habitability Characterization
Kepler-84 d is a confirmed super-earth exoplanet orbiting the star Kepler-84, located approximately 3339.5 light-years (1023.9 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0117% across the stellar disk), this world measures 1.38 Earth radii and has a measured mass of 2.48 Earth masses. Combining its mass and radius yields a mean bulk density of 5.2 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.3 g⊕ (12.75 m/s²), and an escape velocity of 15 km/s.
In its orbital architecture around Kepler-84, Kepler-84 d completes one full revolution every 4.225 Earth days at a semi-major axis of 0.052 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 133.9 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 1254 K (+981°C / +1798°F) and receiving 584.24 S⊕ (~795,151 W/m²), Kepler-84 d 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 6,031 K, a radius of 1.169 R☉, a mass of 1.06 M☉, an estimated bolometric luminosity of 1.622 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 d sharing its stellar neighborhood alongside Kepler-84 b, Kepler-84 c, 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) | 6,031 K |
| Stellar Radius | 1.1690 R☉ |
| Stellar Mass | 1.0600 M☉ |
| Bolometric Luminosity | 1.622 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) | 0.052000 AU |
| Orbital Period | 4.225 days |
| Mean Orbital Velocity | 133.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 82.3100° |
| Mean Bulk Density | 5.2 g/cm³ (15 km/s vesc) |
| Insolation Flux | 584.2400 S⊕ (~795,151 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3339.500 LY (1023.900 pc) |