Kepler-405 b
Astrophysical Synthesis & Habitability Characterization
Kepler-405 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-405, located approximately 3473.8 light-years (1065.08 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0456% across the stellar disk), this world measures 2.08 Earth radii and has a measured mass of 4.98 Earth masses. Combining its mass and radius yields a mean bulk density of 3.05 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.15 g⊕ (11.28 m/s²), and an escape velocity of 17.3 km/s.
In its orbital architecture around Kepler-405, Kepler-405 b completes one full revolution every 10.614 Earth days at a semi-major axis of 0.095 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 97.4 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 785 K (+512°C / +954°F) and receiving 55.62 S⊕ (~75,703 W/m²), Kepler-405 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-405 is classified as a stellar host with an effective photospheric temperature of 5,818 K, a radius of 0.893 R☉, a mass of 0.873 M☉, an estimated bolometric luminosity of 0.82 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.09 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, Kepler-405 shines at apparent V-band magnitude 16.181 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-405 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-405 b sharing its stellar neighborhood alongside Kepler-405 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-405 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,818 K |
| Stellar Radius | 0.8930 R☉ |
| Stellar Mass | 0.8730 M☉ |
| Bolometric Luminosity | 0.82 L☉ |
| Metallicity [Fe/H] | -0.060 dex |
| Stellar Age | 2.090 Gyr |
| Apparent Magnitude | V: 16.181 · G: 15.802 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.095000 AU |
| Orbital Period | 10.614 days |
| Mean Orbital Velocity | 97.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9400° |
| Mean Bulk Density | 3.05 g/cm³ (17.3 km/s vesc) |
| Insolation Flux | 55.6230 S⊕ (~75,703 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3473.800 LY (1065.080 pc) |