Kepler-1503 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1503 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1503, located approximately 3997.3 light-years (1225.57 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0791% across the stellar disk), this world measures 2.27 Earth radii and has a measured mass of 5.77 Earth masses. Combining its mass and radius yields a mean bulk density of 2.72 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.8 km/s.
In its orbital architecture around Kepler-1503, Kepler-1503 b completes one full revolution every 96.17 Earth days at a semi-major axis of 0.3771 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 42.7 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 2.270 R⊕, Kepler-1503 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-1503 is classified as a stellar host with an effective photospheric temperature of 5,069 K, a radius of 0.74 R☉, a mass of 0.77 M☉, an estimated bolometric luminosity of 0.324 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.13 Gyr and a metallicity of [Fe/H] = -0.19 dex (metal-poor relative to the Sun). From Earth, Kepler-1503 shines at apparent V-band magnitude 15.892 (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-1503 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,069 K |
| Stellar Radius | 0.7400 R☉ |
| Stellar Mass | 0.7700 M☉ |
| Bolometric Luminosity | 0.324 L☉ |
| Metallicity [Fe/H] | -0.190 dex |
| Stellar Age | 5.130 Gyr |
| Apparent Magnitude | V: 15.892 · G: 15.786 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.377100 AU |
| Orbital Period | 96.17 days |
| Mean Orbital Velocity | 42.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9700° |
| Mean Bulk Density | 2.72 g/cm³ (17.8 km/s vesc) |
| Insolation Flux | 5.6360 S⊕ (~7,671 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3997.300 LY (1225.570 pc) |