Kepler-127 d
Astrophysical Synthesis & Habitability Characterization
Kepler-127 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-127, located approximately 1150.7 light-years (352.79 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0317% across the stellar disk), this world measures 2.64 Earth radii and has a measured mass of 7.46 Earth masses. Combining its mass and radius yields a mean bulk density of 2.24 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.07 g⊕ (10.49 m/s²), and an escape velocity of 18.8 km/s.
In its orbital architecture around Kepler-127, Kepler-127 d completes one full revolution every 48.63 Earth days at a semi-major axis of 0.28 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 62.6 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.03 (ranging from 0.2716 AU at periapsis to 0.2884 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 590 K (+317°C / +603°F) and receiving 31.52 S⊕ (~42,897 W/m²), Kepler-127 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-127 is classified as a stellar host with an effective photospheric temperature of 6,106 K, a radius of 1.359 R☉, a mass of 1.248 M☉, an estimated bolometric luminosity of 2.303 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.69 Gyr and a metallicity of [Fe/H] = 0.214 dex (metal-rich relative to the Sun). From Earth, Kepler-127 shines at apparent V-band magnitude 11.746 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-127 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-127 d sharing its stellar neighborhood alongside Kepler-127 b, Kepler-127 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-127 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,106 K |
| Stellar Radius | 1.3590 R☉ |
| Stellar Mass | 1.2480 M☉ |
| Bolometric Luminosity | 2.303 L☉ |
| Metallicity [Fe/H] | 0.214 dex |
| Stellar Age | 2.690 Gyr |
| Apparent Magnitude | V: 11.746 · G: 11.438 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.280000 AU |
| Orbital Period | 48.63 days |
| Mean Orbital Velocity | 62.6 km/s |
| Orbital Eccentricity (e) | 0.03000 |
| Orbital Inclination (i) | 89.9600° |
| Mean Bulk Density | 2.24 g/cm³ (18.8 km/s vesc) |
| Insolation Flux | 31.5190 S⊕ (~42,897 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1150.700 LY (352.794 pc) |