Kepler-903 b
Astrophysical Synthesis & Habitability Characterization
Kepler-903 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-903, located approximately 4465.9 light-years (1369.24 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0361% across the stellar disk), this world measures 2.01 Earth radii and has a measured mass of 4.7 Earth masses. Combining its mass and radius yields a mean bulk density of 3.19 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.16 g⊕ (11.38 m/s²), and an escape velocity of 17.1 km/s.
In its orbital architecture around Kepler-903, Kepler-903 b completes one full revolution every 10.351 Earth days at a semi-major axis of 0.09081 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 95.4 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 842 K (+569°C / +1056°F) and receiving 274.85 S⊕ (~374,064 W/m²), Kepler-903 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-903 is classified as a stellar host with an effective photospheric temperature of 5,682 K, a radius of 0.97 R☉, a mass of 0.98 M☉, an estimated bolometric luminosity of 0.88 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.79 Gyr and a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, Kepler-903 shines at apparent V-band magnitude 14.856 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-903 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-903 b sharing its stellar neighborhood alongside Kepler-903 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-903 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,682 K |
| Stellar Radius | 0.9700 R☉ |
| Stellar Mass | 0.9800 M☉ |
| Bolometric Luminosity | 0.88 L☉ |
| Metallicity [Fe/H] | 0.050 dex |
| Stellar Age | 4.790 Gyr |
| Apparent Magnitude | V: 14.856 · G: 14.615 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.090810 AU |
| Orbital Period | 10.351 days |
| Mean Orbital Velocity | 95.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 84.4300° |
| Mean Bulk Density | 3.19 g/cm³ (17.1 km/s vesc) |
| Insolation Flux | 274.8450 S⊕ (~374,064 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4465.900 LY (1369.240 pc) |