Kepler-321 b
Astrophysical Synthesis & Habitability Characterization
Kepler-321 b is a confirmed super-earth exoplanet orbiting the star Kepler-321, located approximately 1254.2 light-years (384.54 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0185% across the stellar disk), this world measures 1.77 Earth radii and has a measured mass of 3.78 Earth masses. Combining its mass and radius yields a mean bulk density of 3.76 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.21 g⊕ (11.87 m/s²), and an escape velocity of 16.3 km/s.
In its orbital architecture around Kepler-321, Kepler-321 b completes one full revolution every 4.915 Earth days at a semi-major axis of 0.057 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 126.2 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 1042 K (+769°C / +1416°F) and receiving 296.16 S⊕ (~403,067 W/m²), Kepler-321 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-321 is classified as a stellar host with an effective photospheric temperature of 5,740 K, a radius of 1.194 R☉, a mass of 1.024 M☉, an estimated bolometric luminosity of 1.389 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.09 Gyr and a metallicity of [Fe/H] = 0.121 dex (metal-rich relative to the Sun). From Earth, Kepler-321 shines at apparent V-band magnitude 12.918 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-321 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-321 b sharing its stellar neighborhood alongside Kepler-321 c.
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-321 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,740 K |
| Stellar Radius | 1.1940 R☉ |
| Stellar Mass | 1.0240 M☉ |
| Bolometric Luminosity | 1.389 L☉ |
| Metallicity [Fe/H] | 0.121 dex |
| Stellar Age | 2.090 Gyr |
| Apparent Magnitude | V: 12.918 · G: 12.755 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.057000 AU |
| Orbital Period | 4.915 days |
| Mean Orbital Velocity | 126.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.7000° |
| Mean Bulk Density | 3.76 g/cm³ (16.3 km/s vesc) |
| Insolation Flux | 296.1550 S⊕ (~403,067 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1254.200 LY (384.542 pc) |