Kepler-553 b
Astrophysical Synthesis & Habitability Characterization
Kepler-553 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-553, located approximately 2376.1 light-years (728.53 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.2322% across the stellar disk), this world measures 4.741 Earth radii (0.42 Jupiter radii) and has a measured mass of 116.007 Earth masses (0.36 Jupiter masses). Combining its mass and radius yields a mean bulk density of 6 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 5.16 g⊕ (50.6 m/s²), and an escape velocity of 55.3 km/s.
In its orbital architecture around Kepler-553, Kepler-553 b completes one full revolution every 4.03 Earth days at a semi-major axis of 0.04766 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 128.6 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 1089 K (+816°C / +1501°F) and receiving 235.00 S⊕ (~319,835 W/m²), Kepler-553 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-553 is classified as a stellar host with an effective photospheric temperature of 5,191 K, a radius of 0.902 R☉, a mass of 0.889 M☉, an estimated bolometric luminosity of 0.53 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.8 Gyr and a metallicity of [Fe/H] = 0.152 dex (metal-rich relative to the Sun). From Earth, Kepler-553 shines at apparent V-band magnitude 15.034 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-553 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-553 b sharing its stellar neighborhood alongside Kepler-553 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-553 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,191 K |
| Stellar Radius | 0.9020 R☉ |
| Stellar Mass | 0.8890 M☉ |
| Bolometric Luminosity | 0.53 L☉ |
| Metallicity [Fe/H] | 0.152 dex |
| Stellar Age | 8.800 Gyr |
| Apparent Magnitude | V: 15.034 · G: 14.957 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.047660 AU |
| Orbital Period | 4.03 days |
| Mean Orbital Velocity | 128.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.9400° |
| Mean Bulk Density | 6 g/cm³ (55.3 km/s vesc) |
| Insolation Flux | 235.0000 S⊕ (~319,835 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2376.100 LY (728.525 pc) |