HAT-P-19 b
Astrophysical Synthesis & Habitability Characterization
HAT-P-19 b is a confirmed gas giant exoplanet orbiting the star HAT-P-19, located approximately 659.1 light-years (202.08 parsecs) from the Solar System. First announced in 2010 by HATNet using the Transit detection technique (producing an estimated primary transit depth of 1.7958% across the stellar disk), this world measures 11.299 Earth radii (1.01 Jupiter radii) and has a measured mass of 88.038 Earth masses (0.28 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.34 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.69 g⊕ (6.77 m/s²), and an escape velocity of 31.2 km/s.
In its orbital architecture around HAT-P-19, HAT-P-19 b completes one full revolution every 4.009 Earth days at a semi-major axis of 0.04599 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 124.8 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.07 carries the world between 0.0428 AU at periapsis and 0.0492 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 981 K (+708°C / +1306°F) and receiving 154.00 S⊕ (~209,594 W/m²), HAT-P-19 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HAT-P-19 is classified as an orange K-type star of spectral type K1 with an effective photospheric temperature of 4,962 K, a radius of 0.773 R☉, a mass of 0.807 M☉, an estimated bolometric luminosity of 0.325 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.2 Gyr and a metallicity of [Fe/H] = 0.166 dex (metal-rich relative to the Sun). From Earth, HAT-P-19 shines at apparent V-band magnitude 12.826 (faint and requiring research-grade or CCD telescopic photometry) 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: HATNet · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HAT-P-19 |
| Spectral Type | K1 |
| Effective Temp (Teff) | 4,962 K |
| Stellar Radius | 0.7730 R☉ |
| Stellar Mass | 0.8070 M☉ |
| Bolometric Luminosity | 0.325 L☉ |
| Metallicity [Fe/H] | 0.166 dex |
| Stellar Age | 7.200 Gyr |
| Apparent Magnitude | V: 12.826 · G: 12.557 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.045990 AU |
| Orbital Period | 4.009 days |
| Mean Orbital Velocity | 124.8 km/s |
| Orbital Eccentricity (e) | 0.07000 |
| Orbital Inclination (i) | 89.5200° |
| Mean Bulk Density | 0.34 g/cm³ (31.2 km/s vesc) |
| Insolation Flux | 154.0000 S⊕ (~209,594 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 659.100 LY (202.078 pc) |