Kepler-401 c
Astrophysical Synthesis & Habitability Characterization
Kepler-401 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-401, located approximately 3149.2 light-years (965.56 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0219% across the stellar disk), this world measures 2.15 Earth radii and has a measured mass of 5.27 Earth masses. Combining its mass and radius yields a mean bulk density of 2.92 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.14 g⊕ (11.18 m/s²), and an escape velocity of 17.5 km/s.
In its orbital architecture around Kepler-401, Kepler-401 c completes one full revolution every 47.318 Earth days at a semi-major axis of 0.269 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 61.8 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 598 K (+325°C / +617°F) and receiving 52.00 S⊕ (~70,767 W/m²), Kepler-401 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-401 is classified as a stellar host with an effective photospheric temperature of 6,117 K, a radius of 1.333 R☉, a mass of 1.173 M☉, an estimated bolometric luminosity of 2.232 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.55 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-401 shines at apparent V-band magnitude 13.366 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-401 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-401 c sharing its stellar neighborhood alongside Kepler-401 b, Kepler-401 d.
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-401 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,117 K |
| Stellar Radius | 1.3330 R☉ |
| Stellar Mass | 1.1730 M☉ |
| Bolometric Luminosity | 2.232 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 3.550 Gyr |
| Apparent Magnitude | V: 13.366 · G: 13.287 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.269000 AU |
| Orbital Period | 47.318 days |
| Mean Orbital Velocity | 61.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.6900° |
| Mean Bulk Density | 2.92 g/cm³ (17.5 km/s vesc) |
| Insolation Flux | 51.9960 S⊕ (~70,767 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3149.200 LY (965.560 pc) |