Kepler-1520 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1520 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1520, located approximately 1982.8 light-years (607.92 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.5551% across the stellar disk), this world measures 5.77 Earth radii (0.51 Jupiter radii) and has a measured mass of 28.1 Earth masses. Combining its mass and radius yields a mean bulk density of 0.81 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.84 g⊕ (8.24 m/s²), and an escape velocity of 24.7 km/s.
In its orbital architecture around Kepler-1520, Kepler-1520 b completes one full revolution every 0.654 Earth days at a semi-major axis of 0.0129 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 214.7 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 1437 K (+1164°C / +2127°F) and receiving 1,134.39 S⊕ (~1,543,899 W/m²), Kepler-1520 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1520 is classified as a stellar host with an effective photospheric temperature of 4,677 K, a radius of 0.71 R☉, a mass of 0.76 M☉, an estimated bolometric luminosity of 0.216 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.47 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, Kepler-1520 shines at apparent V-band magnitude 16.002 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
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-1520 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,677 K |
| Stellar Radius | 0.7100 R☉ |
| Stellar Mass | 0.7600 M☉ |
| Bolometric Luminosity | 0.216 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 4.470 Gyr |
| Apparent Magnitude | V: 16.002 · G: 15.693 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.012900 AU |
| Orbital Period | 0.654 days |
| Mean Orbital Velocity | 214.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 50.9800° |
| Mean Bulk Density | 0.81 g/cm³ (24.7 km/s vesc) |
| Insolation Flux | 1134.3860 S⊕ (~1,543,899 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1982.800 LY (607.917 pc) |