Kepler-554 b
Astrophysical Synthesis & Habitability Characterization
Kepler-554 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-554, located approximately 2252.2 light-years (690.53 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1828% across the stellar disk), this world measures 4.29 Earth radii (0.38 Jupiter radii) and has a measured mass of 17 Earth masses. Combining its mass and radius yields a mean bulk density of 1.19 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 22.3 km/s.
In its orbital architecture around Kepler-554, Kepler-554 b completes one full revolution every 1.902 Earth days at a semi-major axis of 0.03022 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 172.8 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 1346 K (+1073°C / +1963°F) and receiving 877.95 S⊕ (~1,194,883 W/m²), Kepler-554 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-554 is classified as a stellar host with an effective photospheric temperature of 5,447 K, a radius of 0.92 R☉, a mass of 0.93 M☉, an estimated bolometric luminosity of 0.668 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.62 Gyr and a metallicity of [Fe/H] = 0.14 dex (metal-rich relative to the Sun). From Earth, Kepler-554 shines at apparent V-band magnitude 14.49 (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-554 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,447 K |
| Stellar Radius | 0.9200 R☉ |
| Stellar Mass | 0.9300 M☉ |
| Bolometric Luminosity | 0.668 L☉ |
| Metallicity [Fe/H] | 0.140 dex |
| Stellar Age | 5.620 Gyr |
| Apparent Magnitude | V: 14.490 · G: 14.296 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.030220 AU |
| Orbital Period | 1.902 days |
| Mean Orbital Velocity | 172.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.0300° |
| Mean Bulk Density | 1.19 g/cm³ (22.3 km/s vesc) |
| Insolation Flux | 877.9450 S⊕ (~1,194,883 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2252.200 LY (690.525 pc) |