Kepler-255 d
Astrophysical Synthesis & Habitability Characterization
Kepler-255 d is a confirmed super-earth exoplanet orbiting the star Kepler-255, located approximately 3432.9 light-years (1052.53 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0198% across the stellar disk), this world measures 1.32 Earth radii and has a measured mass of 2.3 Earth masses. Combining its mass and radius yields a mean bulk density of 5.51 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.32 g⊕ (12.94 m/s²), and an escape velocity of 14.8 km/s.
In its orbital architecture around Kepler-255, Kepler-255 d completes one full revolution every 1.046 Earth days at a semi-major axis of 0.0192 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 199.8 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 1710 K (+1437°C / +2619°F) and receiving 1,686.09 S⊕ (~2,294,768 W/m²), Kepler-255 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-255 is classified as a stellar host with an effective photospheric temperature of 5,431 K, a radius of 0.86 R☉, a mass of 0.9 M☉, an estimated bolometric luminosity of 0.577 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.37 Gyr and a metallicity of [Fe/H] = 0.02 dex (near-solar heavy-element abundance). From Earth, Kepler-255 shines at apparent V-band magnitude 15.699 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-255 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-255 d sharing its stellar neighborhood alongside Kepler-255 b, Kepler-255 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-255 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,431 K |
| Stellar Radius | 0.8600 R☉ |
| Stellar Mass | 0.9000 M☉ |
| Bolometric Luminosity | 0.577 L☉ |
| Metallicity [Fe/H] | 0.020 dex |
| Stellar Age | 4.370 Gyr |
| Apparent Magnitude | V: 15.699 · G: 15.528 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.019200 AU |
| Orbital Period | 1.046 days |
| Mean Orbital Velocity | 199.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5100° |
| Mean Bulk Density | 5.51 g/cm³ (14.8 km/s vesc) |
| Insolation Flux | 1686.0900 S⊕ (~2,294,768 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3432.900 LY (1052.530 pc) |