Kepler-149 d
Astrophysical Synthesis & Habitability Characterization
Kepler-149 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-149, located approximately 1862.5 light-years (571.03 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1451% across the stellar disk), this world measures 3.96 Earth radii (0.35 Jupiter radii) and has a measured mass of 14.9 Earth masses. Combining its mass and radius yields a mean bulk density of 1.32 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.95 g⊕ (9.32 m/s²), and an escape velocity of 21.7 km/s.
In its orbital architecture around Kepler-149, Kepler-149 d completes one full revolution every 160.018 Earth days at a semi-major axis of 0.571 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 38.8 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.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 3.960 R⊕, Kepler-149 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-149 is classified as a stellar host with an effective photospheric temperature of 5,381 K, a radius of 0.953 R☉, a mass of 1.013 M☉, an estimated bolometric luminosity of 0.683 L☉. Stellar evolution modeling indicates an estimated stellar age of 14 Gyr and a metallicity of [Fe/H] = 0.381 dex (metal-rich relative to the Sun). From Earth, Kepler-149 shines at apparent V-band magnitude 14.152 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-149 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-149 d sharing its stellar neighborhood alongside Kepler-149 b, Kepler-149 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-149 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,381 K |
| Stellar Radius | 0.9530 R☉ |
| Stellar Mass | 1.0130 M☉ |
| Bolometric Luminosity | 0.683 L☉ |
| Metallicity [Fe/H] | 0.381 dex |
| Stellar Age | 14.000 Gyr |
| Apparent Magnitude | V: 14.152 · G: 14.019 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.571000 AU |
| Orbital Period | 160.018 days |
| Mean Orbital Velocity | 38.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.6400° |
| Mean Bulk Density | 1.32 g/cm³ (21.7 km/s vesc) |
| Insolation Flux | 2.4460 S⊕ (~3,329 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1862.500 LY (571.034 pc) |