Kepler-164 d
Astrophysical Synthesis & Habitability Characterization
Kepler-164 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-164, located approximately 2905.3 light-years (890.76 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0383% across the stellar disk), this world measures 2.45 Earth radii and has a measured mass of 6.57 Earth masses. Combining its mass and radius yields a mean bulk density of 2.46 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 18.3 km/s.
In its orbital architecture around Kepler-164, Kepler-164 d completes one full revolution every 28.987 Earth days at a semi-major axis of 0.187 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 70.2 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 637 K (+364°C / +687°F) and receiving 35.89 S⊕ (~48,846 W/m²), Kepler-164 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-164 is classified as a stellar host with an effective photospheric temperature of 5,888 K, a radius of 1.148 R☉, a mass of 1.036 M☉, an estimated bolometric luminosity of 1.421 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.62 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-164 shines at apparent V-band magnitude 14.379 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-164 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-164 d sharing its stellar neighborhood alongside Kepler-164 b, Kepler-164 c, Kepler-164 e.
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-164 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,888 K |
| Stellar Radius | 1.1480 R☉ |
| Stellar Mass | 1.0360 M☉ |
| Bolometric Luminosity | 1.421 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 0.620 Gyr |
| Apparent Magnitude | V: 14.379 · G: 14.233 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.187000 AU |
| Orbital Period | 28.987 days |
| Mean Orbital Velocity | 70.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.6400° |
| Mean Bulk Density | 2.46 g/cm³ (18.3 km/s vesc) |
| Insolation Flux | 35.8900 S⊕ (~48,846 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2905.300 LY (890.758 pc) |