Kepler-550 b
Astrophysical Synthesis & Habitability Characterization
Kepler-550 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-550, located approximately 1735 light-years (531.94 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.2384% across the stellar disk), this world measures 4.42 Earth radii (0.39 Jupiter radii) and has a measured mass of 17.9 Earth masses. Combining its mass and radius yields a mean bulk density of 1.14 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.92 g⊕ (9.02 m/s²), and an escape velocity of 22.5 km/s.
In its orbital architecture around Kepler-550, Kepler-550 b completes one full revolution every 8.6 Earth days at a semi-major axis of 0.0747 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 94.5 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 760 K (+487°C / +909°F) and receiving 77.26 S⊕ (~105,148 W/m²), Kepler-550 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-550 is classified as a stellar host with an effective photospheric temperature of 5,322 K, a radius of 0.83 R☉, a mass of 0.87 M☉, an estimated bolometric luminosity of 0.496 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.68 Gyr and a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, Kepler-550 shines at apparent V-band magnitude 14.626 (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-550 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,322 K |
| Stellar Radius | 0.8300 R☉ |
| Stellar Mass | 0.8700 M☉ |
| Bolometric Luminosity | 0.496 L☉ |
| Metallicity [Fe/H] | -0.020 dex |
| Stellar Age | 4.680 Gyr |
| Apparent Magnitude | V: 14.626 · G: 14.472 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.074700 AU |
| Orbital Period | 8.6 days |
| Mean Orbital Velocity | 94.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.8400° |
| Mean Bulk Density | 1.14 g/cm³ (22.5 km/s vesc) |
| Insolation Flux | 77.2580 S⊕ (~105,148 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1735.000 LY (531.944 pc) |