HD 196885 A b
Astrophysical Synthesis & Habitability Characterization
HD 196885 A b is a confirmed gas giant exoplanet orbiting the star HD 196885 A, located approximately 111.4 light-years (34.17 parsecs) from the Solar System. First announced in 2007 by Haute-Provence Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.2 Earth radii (1.18 Jupiter radii) and has a measured mass of 819.97 Earth masses (2.58 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.97 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.71 g⊕ (46.19 m/s²), and an escape velocity of 88.2 km/s.
In its orbital architecture around HD 196885 A, HD 196885 A b completes one full revolution every 1333 Earth days (3.65Julian years) at a semi-major axis of 2.37 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 19.3 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.48, swinging from 1.2324 AU at periapsis out to 3.5076 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.200 R⊕, HD 196885 A 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 196885 A is classified as a warm F-type star of spectral type F8 V with an effective photospheric temperature of 6,254 K, a radius of 1.31 R☉, a mass of 1.28 M☉, an estimated bolometric luminosity of 2.355 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.12 Gyr and a metallicity of [Fe/H] = 0.22 dex (metal-rich relative to the Sun). From Earth, HD 196885 A shines at apparent V-band magnitude 6.397 (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: Haute-Provence Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 196885 A |
| Spectral Type | F8 V |
| Effective Temp (Teff) | 6,254 K |
| Stellar Radius | 1.3100 R☉ |
| Stellar Mass | 1.2800 M☉ |
| Bolometric Luminosity | 2.355 L☉ |
| Metallicity [Fe/H] | 0.220 dex |
| Stellar Age | 3.120 Gyr |
| Apparent Magnitude | V: 6.397 · G: 6.261 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.370000 AU |
| Orbital Period | 1333 days |
| Mean Orbital Velocity | 19.3 km/s |
| Orbital Eccentricity (e) | 0.48000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.97 g/cm³ (88.2 km/s vesc) |
| Insolation Flux | 0.4271 S⊕ (~581 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 111.400 LY (34.169 pc) |