HD 43197 b
Astrophysical Synthesis & Habitability Characterization
HD 43197 b is a confirmed gas giant exoplanet orbiting the star HD 43197, located approximately 203.6 light-years (62.41 parsecs) from the Solar System. First announced in 2010 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 14.2 Earth radii (1.27 Jupiter radii) and has a measured mass of 175.759 Earth masses (0.55 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 0.87 g⊕ (8.53 m/s²), and an escape velocity of 39.4 km/s.
In its orbital architecture around HD 43197, HD 43197 b completes one full revolution every 308.921 Earth days at a semi-major axis of 0.882 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 31.1 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.742, swinging from 0.2276 AU at periapsis out to 1.5364 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 14.200 R⊕, HD 43197 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 43197 is classified as a solar-type yellow star of spectral type G8 V with an effective photospheric temperature of 5,508 K, a radius of 1 R☉, a mass of 0.96 M☉, an estimated bolometric luminosity of 0.826 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.4 dex (metal-rich relative to the Sun). From Earth, HD 43197 shines at apparent V-band magnitude 8.98 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 43197 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 43197 b sharing its stellar neighborhood alongside HD 43197 c.
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 43197 |
| Spectral Type | G8 V |
| Effective Temp (Teff) | 5,508 K |
| Stellar Radius | 1.0000 R☉ |
| Stellar Mass | 0.9600 M☉ |
| Bolometric Luminosity | 0.826 L☉ |
| Metallicity [Fe/H] | 0.400 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.980 · G: 8.772 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.882000 AU |
| Orbital Period | 308.921 days |
| Mean Orbital Velocity | 31.1 km/s |
| Orbital Eccentricity (e) | 0.74200 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.34 g/cm³ (39.4 km/s vesc) |
| Insolation Flux | 0.9377 S⊕ (~1,276 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 203.600 LY (62.411 pc) |