Kepler-619 d
Astrophysical Synthesis & Habitability Characterization
Kepler-619 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-619, located approximately 2937.6 light-years (900.68 parsecs) from the Solar System. First announced in 2023 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1573% across the stellar disk), this world measures 4.17 Earth radii (0.37 Jupiter radii) and has a measured mass of 16.2 Earth masses. Combining its mass and radius yields a mean bulk density of 1.23 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.93 g⊕ (9.12 m/s²), and an escape velocity of 22 km/s.
In its orbital architecture around Kepler-619, Kepler-619 d completes one full revolution every 11.679 Earth days at a semi-major axis of 0.1021 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 95.1 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 830 K (+557°C / +1035°F) and receiving 112.07 S⊕ (~152,527 W/m²), Kepler-619 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-619 is classified as a stellar host with an effective photospheric temperature of 6,122 K, a radius of 0.964 R☉, a mass of 1.041 M☉, an estimated bolometric luminosity of 1.171 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.78 Gyr and a metallicity of [Fe/H] = -0.18 dex (metal-poor relative to the Sun). From Earth, Kepler-619 shines at apparent V-band magnitude 14.84 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-619 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-619 d sharing its stellar neighborhood alongside Kepler-619 c, Kepler-619 b.
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-619 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,122 K |
| Stellar Radius | 0.9640 R☉ |
| Stellar Mass | 1.0410 M☉ |
| Bolometric Luminosity | 1.171 L☉ |
| Metallicity [Fe/H] | -0.180 dex |
| Stellar Age | 0.780 Gyr |
| Apparent Magnitude | V: 14.840 · G: 14.670 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.102100 AU |
| Orbital Period | 11.679 days |
| Mean Orbital Velocity | 95.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.2800° |
| Mean Bulk Density | 1.23 g/cm³ (22 km/s vesc) |
| Insolation Flux | 112.0700 S⊕ (~152,527 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2937.600 LY (900.678 pc) |