Kepler-275 d
Astrophysical Synthesis & Habitability Characterization
Kepler-275 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-275, located approximately 6634.8 light-years (2034.25 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0487% across the stellar disk), this world measures 3.33 Earth radii (0.3 Jupiter radii) and has a measured mass of 11.1 Earth masses. Combining its mass and radius yields a mean bulk density of 1.66 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1 g⊕ (9.81 m/s²), and an escape velocity of 20.4 km/s.
In its orbital architecture around Kepler-275, Kepler-275 d completes one full revolution every 35.676 Earth days at a semi-major axis of 0.224 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 68.3 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 671 K (+398°C / +748°F) and receiving 50.70 S⊕ (~69,003 W/m²), Kepler-275 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-275 is classified as a stellar host with an effective photospheric temperature of 6,165 K, a radius of 1.383 R☉, a mass of 1.189 M☉, an estimated bolometric luminosity of 2.479 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.39 Gyr and a metallicity of [Fe/H] = 0.08 dex (metal-rich relative to the Sun). From Earth, Kepler-275 shines at apparent V-band magnitude 15.289 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-275 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-275 d sharing its stellar neighborhood alongside Kepler-275 b, Kepler-275 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-275 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,165 K |
| Stellar Radius | 1.3830 R☉ |
| Stellar Mass | 1.1890 M☉ |
| Bolometric Luminosity | 2.479 L☉ |
| Metallicity [Fe/H] | 0.080 dex |
| Stellar Age | 3.390 Gyr |
| Apparent Magnitude | V: 15.289 · G: 15.287 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.224000 AU |
| Orbital Period | 35.676 days |
| Mean Orbital Velocity | 68.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.8400° |
| Mean Bulk Density | 1.66 g/cm³ (20.4 km/s vesc) |
| Insolation Flux | 50.7000 S⊕ (~69,003 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 6634.800 LY (2034.250 pc) |