Kepler-245 d
Astrophysical Synthesis & Habitability Characterization
Kepler-245 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-245, located approximately 2809.9 light-years (861.53 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1221% across the stellar disk), this world measures 3.03 Earth radii (0.27 Jupiter radii) and has a measured mass of 21.6 Earth masses. Combining its mass and radius yields a mean bulk density of 4.28 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 2.35 g⊕ (23.05 m/s²), and an escape velocity of 29.9 km/s.
In its orbital architecture around Kepler-245, Kepler-245 d completes one full revolution every 36.277 Earth days at a semi-major axis of 0.202 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 60.6 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 445 K (+172°C / +342°F) and receiving 9.49 S⊕ (~12,919 W/m²), Kepler-245 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-245 is classified as a stellar host with an effective photospheric temperature of 5,100 K, a radius of 0.795 R☉, a mass of 0.856 M☉, an estimated bolometric luminosity of 0.384 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.63 Gyr and a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, Kepler-245 shines at apparent V-band magnitude 15.546 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-245 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-245 d sharing its stellar neighborhood alongside Kepler-245 e, Kepler-245 b, Kepler-245 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-245 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,100 K |
| Stellar Radius | 0.7950 R☉ |
| Stellar Mass | 0.8560 M☉ |
| Bolometric Luminosity | 0.384 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | 3.630 Gyr |
| Apparent Magnitude | V: 15.546 · G: 15.597 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.202000 AU |
| Orbital Period | 36.277 days |
| Mean Orbital Velocity | 60.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9700° |
| Mean Bulk Density | 4.28 g/cm³ (29.9 km/s vesc) |
| Insolation Flux | 9.4920 S⊕ (~12,919 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2809.900 LY (861.527 pc) |