Kepler-30 d
Astrophysical Synthesis & Habitability Characterization
Kepler-30 d is a confirmed gas giant exoplanet orbiting the star Kepler-30, located approximately 2981.8 light-years (914.22 parsecs) from the Solar System. First announced in 2012 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.7212% across the stellar disk), this world measures 8.8 Earth radii (0.79 Jupiter radii) and has a measured mass of 23.1 Earth masses. Combining its mass and radius yields a mean bulk density of 0.19 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.3 g⊕ (2.94 m/s²), and an escape velocity of 18.1 km/s.
In its orbital architecture around Kepler-30, Kepler-30 d completes one full revolution every 143.344 Earth days at a semi-major axis of 0.5 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 37.9 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.022 (ranging from 0.489 AU at periapsis to 0.511 AU at apoapsis), the planet experiences minimal orbital distance variation.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 8.800 R⊕, Kepler-30 d exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star Kepler-30 is classified as a stellar host with an effective photospheric temperature of 5,498 K, a radius of 0.95 R☉, a mass of 0.99 M☉, an estimated bolometric luminosity of 0.74 L☉. Stellar evolution modeling indicates an estimated stellar age of 2 Gyr and a metallicity of [Fe/H] = 0.18 dex (metal-rich relative to the Sun). From Earth, Kepler-30 shines at apparent V-band magnitude 15.726 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-30 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-30 d sharing its stellar neighborhood alongside Kepler-30 b, Kepler-30 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-30 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,498 K |
| Stellar Radius | 0.9500 R☉ |
| Stellar Mass | 0.9900 M☉ |
| Bolometric Luminosity | 0.74 L☉ |
| Metallicity [Fe/H] | 0.180 dex |
| Stellar Age | 2.000 Gyr |
| Apparent Magnitude | V: 15.726 · G: 15.376 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.500000 AU |
| Orbital Period | 143.344 days |
| Mean Orbital Velocity | 37.9 km/s |
| Orbital Eccentricity (e) | 0.02200 |
| Orbital Inclination (i) | 89.8406° |
| Mean Bulk Density | 0.19 g/cm³ (18.1 km/s vesc) |
| Insolation Flux | 1.9620 S⊕ (~2,670 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2981.800 LY (914.221 pc) |