Kepler-1533 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1533 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1533, located approximately 3153.3 light-years (966.8 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0441% across the stellar disk), this world measures 3.46 Earth radii (0.31 Jupiter radii) and has a measured mass of 11.8 Earth masses. Combining its mass and radius yields a mean bulk density of 1.57 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.99 g⊕ (9.71 m/s²), and an escape velocity of 20.7 km/s.
In its orbital architecture around Kepler-1533, Kepler-1533 b completes one full revolution every 308.547 Earth days at a semi-major axis of 0.93416 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 32.9 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.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 3.460 R⊕, Kepler-1533 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star Kepler-1533 is classified as a stellar host with an effective photospheric temperature of 6,431 K, a radius of 1.51 R☉, a mass of 1.31 M☉, an estimated bolometric luminosity of 3.499 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.19 Gyr and a metallicity of [Fe/H] = 0.03 dex (near-solar heavy-element abundance). From Earth, Kepler-1533 shines at apparent V-band magnitude 13.289 (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-1533 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,431 K |
| Stellar Radius | 1.5100 R☉ |
| Stellar Mass | 1.3100 M☉ |
| Bolometric Luminosity | 3.499 L☉ |
| Metallicity [Fe/H] | 0.030 dex |
| Stellar Age | 2.190 Gyr |
| Apparent Magnitude | V: 13.289 · G: 13.168 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.934160 AU |
| Orbital Period | 308.547 days |
| Mean Orbital Velocity | 32.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9900° |
| Mean Bulk Density | 1.57 g/cm³ (20.7 km/s vesc) |
| Insolation Flux | 4.7860 S⊕ (~6,514 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3153.300 LY (966.801 pc) |