Kepler-54 d
Astrophysical Synthesis & Habitability Characterization
Kepler-54 d is a confirmed super-earth exoplanet orbiting the star Kepler-54, located approximately 886.2 light-years (271.7 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0641% across the stellar disk), this world measures 1.53 Earth radii and has a measured mass of 12.095 Earth masses. Combining its mass and radius yields a mean bulk density of 18.62 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 5.17 g⊕ (50.7 m/s²), and an escape velocity of 31.5 km/s.
In its orbital architecture around Kepler-54, Kepler-54 d completes one full revolution every 20.996 Earth days at a semi-major axis of 0.126 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 65.3 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.
ℹ️ Thermal & Atmospheric Regime: Current photometric and spectroscopic constraints for Kepler-54 d place it outside the conservative habitable zone definition pending further atmospheric characterization.
The host star Kepler-54 is classified as a low-mass red dwarf of spectral type M1 V with an effective photospheric temperature of 4,252 K, a radius of 0.554 R☉, a mass of 0.518 M☉, an estimated bolometric luminosity of 0.09 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.83 Gyr and a metallicity of [Fe/H] = -0.27 dex (metal-poor relative to the Sun). From Earth, Kepler-54 shines at apparent V-band magnitude 16.282 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-54 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-54 d sharing its stellar neighborhood alongside Kepler-54 b, Kepler-54 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-54 |
| Spectral Type | M1 V |
| Effective Temp (Teff) | 4,252 K |
| Stellar Radius | 0.5540 R☉ |
| Stellar Mass | 0.5180 M☉ |
| Bolometric Luminosity | 0.09 L☉ |
| Metallicity [Fe/H] | -0.270 dex |
| Stellar Age | 4.830 Gyr |
| Apparent Magnitude | V: 16.282 · G: 15.813 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.126000 AU |
| Orbital Period | 20.996 days |
| Mean Orbital Velocity | 65.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.7900° |
| Mean Bulk Density | 18.62 g/cm³ (31.5 km/s vesc) |
| Insolation Flux | 3.4250 S⊕ (~4,661 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 886.200 LY (271.701 pc) |