Kepler-80 d
Astrophysical Synthesis & Habitability Characterization
Kepler-80 d is a confirmed super-earth exoplanet orbiting the star Kepler-80, located approximately 1205 light-years (369.45 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0428% across the stellar disk), this world measures 1.53 Earth radii and has a measured mass of 6.75 Earth masses. Combining its mass and radius yields a mean bulk density of 10.39 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 2.88 g⊕ (28.24 m/s²), and an escape velocity of 23.5 km/s.
In its orbital architecture around Kepler-80, Kepler-80 d completes one full revolution every 3.072 Earth days at a semi-major axis of 0.0372 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 131.7 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.0041 (ranging from 0.037 AU at periapsis to 0.0374 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 722 K (+449°C / +840°F) and receiving 164.63 S⊕ (~224,055 W/m²), Kepler-80 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-80 is classified as an orange K-type star of spectral type K5 with an effective photospheric temperature of 4,540 K, a radius of 0.678 R☉, a mass of 0.73 M☉, an estimated bolometric luminosity of 0.175 L☉. Stellar evolution modeling indicates an estimated stellar age of 2 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, Kepler-80 shines at apparent V-band magnitude 15.23 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-80 system is a multi-planet architecture hosting 6 confirmed worlds, with Kepler-80 d sharing its stellar neighborhood alongside Kepler-80 f, Kepler-80 e, Kepler-80 b, Kepler-80 c, Kepler-80 g.
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-80 |
| Spectral Type | K5 |
| Effective Temp (Teff) | 4,540 K |
| Stellar Radius | 0.6780 R☉ |
| Stellar Mass | 0.7300 M☉ |
| Bolometric Luminosity | 0.175 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 2.000 Gyr |
| Apparent Magnitude | V: 15.230 · G: 14.756 |
| System Architecture | 1 Star, 6 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.037200 AU |
| Orbital Period | 3.072 days |
| Mean Orbital Velocity | 131.7 km/s |
| Orbital Eccentricity (e) | 0.00410 |
| Orbital Inclination (i) | 88.3500° |
| Mean Bulk Density | 10.39 g/cm³ (23.5 km/s vesc) |
| Insolation Flux | 164.6250 S⊕ (~224,055 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1205.000 LY (369.451 pc) |