Kepler-394 d
Astrophysical Synthesis & Habitability Characterization
Kepler-394 d is a confirmed super-earth exoplanet orbiting the star Kepler-394, located approximately 3453.1 light-years (1058.72 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0156% across the stellar disk), this world measures 1.501 Earth radii and has a measured mass of 2.86 Earth masses. Combining its mass and radius yields a mean bulk density of 4.66 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.27 g⊕ (12.45 m/s²), and an escape velocity of 15.4 km/s.
In its orbital architecture around Kepler-394, Kepler-394 d completes one full revolution every 5.614 Earth days at a semi-major axis of 0.05904 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 114.4 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 1165 K (+892°C / +1638°F) and receiving 302.00 S⊕ (~411,022 W/m²), Kepler-394 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-394 is classified as a stellar host with an effective photospheric temperature of 6,398 K, a radius of 1.101 R☉, a mass of 1.141 M☉, an estimated bolometric luminosity of 1.822 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.25 Gyr and a metallicity of [Fe/H] = -0.14 dex (metal-poor relative to the Sun). From Earth, Kepler-394 shines at apparent V-band magnitude 14.948 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-394 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-394 d sharing its stellar neighborhood alongside Kepler-394 b, Kepler-394 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-394 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,398 K |
| Stellar Radius | 1.1010 R☉ |
| Stellar Mass | 1.1410 M☉ |
| Bolometric Luminosity | 1.822 L☉ |
| Metallicity [Fe/H] | -0.140 dex |
| Stellar Age | 0.250 Gyr |
| Apparent Magnitude | V: 14.948 · G: 14.770 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.059040 AU |
| Orbital Period | 5.614 days |
| Mean Orbital Velocity | 114.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5400° |
| Mean Bulk Density | 4.66 g/cm³ (15.4 km/s vesc) |
| Insolation Flux | 302.0000 S⊕ (~411,022 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3453.100 LY (1058.720 pc) |