Kepler-603 b
Astrophysical Synthesis & Habitability Characterization
Kepler-603 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-603, located approximately 5021.6 light-years (1539.63 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0579% across the stellar disk), this world measures 2.65 Earth radii and has a measured mass of 7.51 Earth masses. Combining its mass and radius yields a mean bulk density of 2.23 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.07 g⊕ (10.49 m/s²), and an escape velocity of 18.8 km/s.
In its orbital architecture around Kepler-603, Kepler-603 b completes one full revolution every 21.054 Earth days at a semi-major axis of 0.16052 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 82.9 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.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 731 K (+458°C / +856°F) and receiving 97.80 S⊕ (~133,106 W/m²), Kepler-603 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-603 is classified as a stellar host with an effective photospheric temperature of 5,808 K, a radius of 1.01 R☉, a mass of 1.01 M☉, an estimated bolometric luminosity of 1.041 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.37 Gyr and a metallicity of [Fe/H] = 0.03 dex (near-solar heavy-element abundance). From Earth, Kepler-603 shines at apparent V-band magnitude 14.969 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-603 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-603 b sharing its stellar neighborhood alongside Kepler-603 d, Kepler-603 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-603 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,808 K |
| Stellar Radius | 1.0100 R☉ |
| Stellar Mass | 1.0100 M☉ |
| Bolometric Luminosity | 1.041 L☉ |
| Metallicity [Fe/H] | 0.030 dex |
| Stellar Age | 4.370 Gyr |
| Apparent Magnitude | V: 14.969 · G: 14.816 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.160520 AU |
| Orbital Period | 21.054 days |
| Mean Orbital Velocity | 82.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9800° |
| Mean Bulk Density | 2.23 g/cm³ (18.8 km/s vesc) |
| Insolation Flux | 97.8000 S⊕ (~133,106 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 5021.600 LY (1539.630 pc) |