Kepler-215 d
Astrophysical Synthesis & Habitability Characterization
Kepler-215 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-215, located approximately 1585.1 light-years (486 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0455% across the stellar disk), this world measures 2.39 Earth radii and has a measured mass of 23.6 Earth masses. Combining its mass and radius yields a mean bulk density of 9.53 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 4.13 g⊕ (40.5 m/s²), and an escape velocity of 35.2 km/s.
In its orbital architecture around Kepler-215, Kepler-215 d completes one full revolution every 30.864 Earth days at a semi-major axis of 0.185 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 65.2 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 527 K (+254°C / +489°F) and receiving 21.40 S⊕ (~29,131 W/m²), Kepler-215 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-215 is classified as a stellar host with an effective photospheric temperature of 5,739 K, a radius of 1.027 R☉, a mass of 0.788 M☉, an estimated bolometric luminosity of 1.027 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.62 Gyr and a metallicity of [Fe/H] = -0.443 dex (metal-poor relative to the Sun). From Earth, Kepler-215 shines at apparent V-band magnitude 13.678 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-215 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-215 d sharing its stellar neighborhood alongside Kepler-215 b, Kepler-215 c, Kepler-215 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-215 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,739 K |
| Stellar Radius | 1.0270 R☉ |
| Stellar Mass | 0.7880 M☉ |
| Bolometric Luminosity | 1.027 L☉ |
| Metallicity [Fe/H] | -0.443 dex |
| Stellar Age | 1.620 Gyr |
| Apparent Magnitude | V: 13.678 · G: 13.555 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.185000 AU |
| Orbital Period | 30.864 days |
| Mean Orbital Velocity | 65.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.9300° |
| Mean Bulk Density | 9.53 g/cm³ (35.2 km/s vesc) |
| Insolation Flux | 21.4040 S⊕ (~29,131 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1585.100 LY (485.997 pc) |