KELT-19 A b
Astrophysical Synthesis & Habitability Characterization
KELT-19 A b is a confirmed gas giant exoplanet orbiting the star KELT-19 A, located approximately 979.4 light-years (300.28 parsecs) from the Solar System. First announced in 2017 by KELT using the Transit detection technique (producing an estimated primary transit depth of 1.1504% across the stellar disk), this world measures 21.409 Earth radii (1.91 Jupiter radii) and has a measured mass of 1293.568 Earth masses (4.07 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.73 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.82 g⊕ (27.65 m/s²), and an escape velocity of 87 km/s.
In its orbital architecture around KELT-19 A, KELT-19 A b completes one full revolution every 4.612 Earth days at a semi-major axis of 0.0637 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 150.3 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1935 K (+1662°C / +3024°F) and receiving 2,340.00 S⊕ (~3,184,740 W/m²), KELT-19 A b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star KELT-19 A is classified as a luminous A-type star of spectral type A8 V with an effective photospheric temperature of 7,500 K, a radius of 1.83 R☉, a mass of 1.62 M☉, an estimated bolometric luminosity of 9.507 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.12 dex (metal-poor relative to the Sun). From Earth, KELT-19 A shines at apparent V-band magnitude 9.857 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere.
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: KELT · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | KELT-19 A |
| Spectral Type | A8 V |
| Effective Temp (Teff) | 7,500 K |
| Stellar Radius | 1.8300 R☉ |
| Stellar Mass | 1.6200 M☉ |
| Bolometric Luminosity | 9.507 L☉ |
| Metallicity [Fe/H] | -0.120 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.857 · G: 9.863 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.063700 AU |
| Orbital Period | 4.612 days |
| Mean Orbital Velocity | 150.3 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 85.4100° |
| Mean Bulk Density | 0.73 g/cm³ (87 km/s vesc) |
| Insolation Flux | 2340.0000 S⊕ (~3,184,740 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 979.400 LY (300.276 pc) |