HD 202206 c
Astrophysical Synthesis & Habitability Characterization
HD 202206 c is a confirmed gas giant exoplanet orbiting the star HD 202206, located approximately 149.9 light-years (45.97 parsecs) from the Solar System. First announced in 2004 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.1 Earth radii (1.17 Jupiter radii) and has a measured mass of 982.09 Earth masses (3.09 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.41 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 5.72 g⊕ (56.09 m/s²), and an escape velocity of 96.9 km/s.
In its orbital architecture around HD 202206, HD 202206 c completes one full revolution every 1299.22 Earth days (3.56Julian years) at a semi-major axis of 2.39 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 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.171 carries the world between 1.9813 AU at periapsis and 2.7987 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.100 R⊕, HD 202206 c 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 202206 is classified as a solar-type yellow star of spectral type G2 V with an effective photospheric temperature of 5,764 K, a radius of 1.04 R☉, a mass of 1.06 M☉, an estimated bolometric luminosity of 1.071 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.94 Gyr and a metallicity of [Fe/H] = 0.23 dex (metal-rich relative to the Sun). From Earth, HD 202206 shines at apparent V-band magnitude 8.08 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 202206 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 202206 c sharing its stellar neighborhood alongside HD 202206 b.
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 202206 |
| Spectral Type | G2 V |
| Effective Temp (Teff) | 5,764 K |
| Stellar Radius | 1.0400 R☉ |
| Stellar Mass | 1.0600 M☉ |
| Bolometric Luminosity | 1.071 L☉ |
| Metallicity [Fe/H] | 0.230 dex |
| Stellar Age | 3.940 Gyr |
| Apparent Magnitude | V: 8.080 · G: 7.911 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.390000 AU |
| Orbital Period | 1299.22 days |
| Mean Orbital Velocity | 20 km/s |
| Orbital Eccentricity (e) | 0.17100 |
| Orbital Inclination (i) | 51.0000° |
| Mean Bulk Density | 2.41 g/cm³ (96.9 km/s vesc) |
| Insolation Flux | 0.1908 S⊕ (~260 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 149.900 LY (45.967 pc) |