Kepler-48 d
Astrophysical Synthesis & Habitability Characterization
Kepler-48 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-48, located approximately 1000.4 light-years (306.74 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0442% across the stellar disk), this world measures 2.04 Earth radii and has a measured mass of 7.93 Earth masses. Combining its mass and radius yields a mean bulk density of 5.15 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.91 g⊕ (18.73 m/s²), and an escape velocity of 22.1 km/s.
In its orbital architecture around Kepler-48, Kepler-48 d completes one full revolution every 42.896 Earth days at a semi-major axis of 0.23302 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 59.1 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 448 K (+175°C / +347°F) and receiving 9.29 S⊕ (~12,646 W/m²), Kepler-48 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-48 is classified as a stellar host with an effective photospheric temperature of 5,194 K, a radius of 0.89 R☉, a mass of 0.88 M☉, an estimated bolometric luminosity of 0.517 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.14 Gyr and a metallicity of [Fe/H] = 0.17 dex (metal-rich relative to the Sun). From Earth, Kepler-48 shines at apparent V-band magnitude 13.174 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-48 system is a multi-planet architecture hosting 5 confirmed worlds, with Kepler-48 d sharing its stellar neighborhood alongside Kepler-48 b, Kepler-48 c, Kepler-48 e, Kepler-48 f.
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-48 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,194 K |
| Stellar Radius | 0.8900 R☉ |
| Stellar Mass | 0.8800 M☉ |
| Bolometric Luminosity | 0.517 L☉ |
| Metallicity [Fe/H] | 0.170 dex |
| Stellar Age | 3.140 Gyr |
| Apparent Magnitude | V: 13.174 · G: 13.077 |
| System Architecture | 1 Star, 5 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.233020 AU |
| Orbital Period | 42.896 days |
| Mean Orbital Velocity | 59.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9900° |
| Mean Bulk Density | 5.15 g/cm³ (22.1 km/s vesc) |
| Insolation Flux | 9.2920 S⊕ (~12,646 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1000.400 LY (306.738 pc) |