HD 82943 c
Astrophysical Synthesis & Habitability Characterization
HD 82943 c is a confirmed gas giant exoplanet orbiting the star HD 82943, located approximately 90 light-years (27.59 parsecs) from the Solar System. First announced in 2003 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 622.603 Earth masses (1.96 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.43 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.47 g⊕ (34.03 m/s²), and an escape velocity of 76.2 km/s.
In its orbital architecture around HD 82943, HD 82943 c completes one full revolution every 220.078 Earth days at a semi-major axis of 0.74345 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 36.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.3663, swinging from 0.4711 AU at periapsis out to 1.0158 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 361 K (+88°C / +190°F) and receiving 2.83 S⊕ (~3,850 W/m²), HD 82943 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 82943 is classified as a solar-type yellow star of spectral type G2/3V with an effective photospheric temperature of 5,935 K, a radius of 1.1826 R☉, a mass of 1.08 M☉, an estimated bolometric luminosity of 1.557 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.35 Gyr and a metallicity of [Fe/H] = 0.26 dex (metal-rich relative to the Sun). From Earth, HD 82943 shines at apparent V-band magnitude 6.55 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 82943 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 82943 c sharing its stellar neighborhood alongside HD 82943 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 82943 |
| Spectral Type | G2/3V |
| Effective Temp (Teff) | 5,935 K |
| Stellar Radius | 1.1826 R☉ |
| Stellar Mass | 1.0800 M☉ |
| Bolometric Luminosity | 1.557 L☉ |
| Metallicity [Fe/H] | 0.260 dex |
| Stellar Age | 2.350 Gyr |
| Apparent Magnitude | V: 6.550 · G: 6.390 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.743450 AU |
| Orbital Period | 220.078 days |
| Mean Orbital Velocity | 36.8 km/s |
| Orbital Eccentricity (e) | 0.36630 |
| Orbital Inclination (i) | 90.0000° |
| Mean Bulk Density | 1.43 g/cm³ (76.2 km/s vesc) |
| Insolation Flux | 2.8285 S⊕ (~3,850 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 90.000 LY (27.590 pc) |