Kepler-529 d
Astrophysical Synthesis & Habitability Characterization
Kepler-529 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-529, located approximately 2606 light-years (799.01 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0464% across the stellar disk), this world measures 2.795 Earth radii and has a measured mass of 8.22 Earth masses. Combining its mass and radius yields a mean bulk density of 2.08 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.2 km/s.
In its orbital architecture around Kepler-529, Kepler-529 d completes one full revolution every 35.866 Earth days at a semi-major axis of 0.2134 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 64.7 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 633 K (+360°C / +680°F) and receiving 37.92 S⊕ (~51,609 W/m²), Kepler-529 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-529 is classified as a stellar host with an effective photospheric temperature of 6,078 K, a radius of 1.189 R☉, a mass of 1.005 M☉, an estimated bolometric luminosity of 1.731 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.2 Gyr and a metallicity of [Fe/H] = -0.16 dex (metal-poor relative to the Sun). From Earth, Kepler-529 shines at apparent V-band magnitude 13.779 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-529 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-529 d sharing its stellar neighborhood alongside Kepler-529 b, Kepler-529 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-529 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,078 K |
| Stellar Radius | 1.1890 R☉ |
| Stellar Mass | 1.0050 M☉ |
| Bolometric Luminosity | 1.731 L☉ |
| Metallicity [Fe/H] | -0.160 dex |
| Stellar Age | 0.200 Gyr |
| Apparent Magnitude | V: 13.779 · G: 13.740 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.213400 AU |
| Orbital Period | 35.866 days |
| Mean Orbital Velocity | 64.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 85.1400° |
| Mean Bulk Density | 2.08 g/cm³ (19.2 km/s vesc) |
| Insolation Flux | 37.9200 S⊕ (~51,609 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2606.000 LY (799.008 pc) |