Kepler-45 b
Astrophysical Synthesis & Habitability Characterization
Kepler-45 b is a confirmed gas giant exoplanet orbiting the star Kepler-45, located approximately 1245.7 light-years (381.95 parsecs) from the Solar System. First announced in 2011 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 3.2169% across the stellar disk), this world measures 10.76 Earth radii (0.96 Jupiter radii) and has a measured mass of 160.497 Earth masses (0.5 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.71 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.39 g⊕ (13.63 m/s²), and an escape velocity of 43.2 km/s.
In its orbital architecture around Kepler-45, Kepler-45 b completes one full revolution every 2.455 Earth days at a semi-major axis of 0.03 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 132.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.11 carries the world between 0.0267 AU at periapsis and 0.0333 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1000 K (+727°C / +1341°F) and receiving 68.37 S⊕ (~93,052 W/m²), Kepler-45 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-45 is classified as a low-mass red dwarf of spectral type M with an effective photospheric temperature of 3,820 K, a radius of 0.55 R☉, a mass of 0.59 M☉, an estimated bolometric luminosity of 0.058 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.5 Gyr and a metallicity of [Fe/H] = 0.28 dex (metal-rich relative to the Sun). From Earth, Kepler-45 shines at apparent V-band magnitude 16.744 (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-45 |
| Spectral Type | M |
| Effective Temp (Teff) | 3,820 K |
| Stellar Radius | 0.5500 R☉ |
| Stellar Mass | 0.5900 M☉ |
| Bolometric Luminosity | 0.058 L☉ |
| Metallicity [Fe/H] | 0.280 dex |
| Stellar Age | 0.500 Gyr |
| Apparent Magnitude | V: 16.744 · G: 15.980 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.030000 AU |
| Orbital Period | 2.455 days |
| Mean Orbital Velocity | 132.9 km/s |
| Orbital Eccentricity (e) | 0.11000 |
| Orbital Inclination (i) | 87.0000° |
| Mean Bulk Density | 0.71 g/cm³ (43.2 km/s vesc) |
| Insolation Flux | 68.3700 S⊕ (~93,052 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1245.700 LY (381.949 pc) |