HD 190647 b
Astrophysical Synthesis & Habitability Characterization
HD 190647 b is a confirmed gas giant exoplanet orbiting the star HD 190647, located approximately 177.7 light-years (54.47 parsecs) from the Solar System. First announced in 2007 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.4 Earth radii (1.2 Jupiter radii) and has a measured mass of 630.893 Earth masses (1.99 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.45 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.51 g⊕ (34.42 m/s²), and an escape velocity of 76.8 km/s.
In its orbital architecture around HD 190647, HD 190647 b completes one full revolution every 1176.45 Earth days (3.22Julian years) at a semi-major axis of 2.231 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 20.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.224 carries the world between 1.7313 AU at periapsis and 2.7307 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.400 R⊕, HD 190647 b 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 HD 190647 is classified as a solar-type yellow star of spectral type G5 V with an effective photospheric temperature of 5,656 K, a radius of 1.376 R☉, a mass of 1.069 M☉, an estimated bolometric luminosity of 1.738 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.957 Gyr and a metallicity of [Fe/H] = 0.23 dex (metal-rich relative to the Sun). From Earth, HD 190647 shines at apparent V-band magnitude 7.78 (accessible to binoculars and small amateur telescopes) in the Southern 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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 190647 |
| Spectral Type | G5 V |
| Effective Temp (Teff) | 5,656 K |
| Stellar Radius | 1.3760 R☉ |
| Stellar Mass | 1.0690 M☉ |
| Bolometric Luminosity | 1.738 L☉ |
| Metallicity [Fe/H] | 0.230 dex |
| Stellar Age | 7.957 Gyr |
| Apparent Magnitude | V: 7.780 · G: 7.594 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.231000 AU |
| Orbital Period | 1176.45 days |
| Mean Orbital Velocity | 20.6 km/s |
| Orbital Eccentricity (e) | 0.22400 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.45 g/cm³ (76.8 km/s vesc) |
| Insolation Flux | 0.3978 S⊕ (~541 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 177.700 LY (54.474 pc) |