HD 290327 b
Astrophysical Synthesis & Habitability Characterization
HD 290327 b is a confirmed gas giant exoplanet orbiting the star HD 290327, located approximately 184.1 light-years (56.43 parsecs) from the Solar System. First announced in 2009 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.3 Earth radii (1.19 Jupiter radii) and has a measured mass of 772.327 Earth masses (2.43 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.81 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.37 g⊕ (42.86 m/s²), and an escape velocity of 85.2 km/s.
In its orbital architecture around HD 290327, HD 290327 b completes one full revolution every 2443 Earth days (6.69Julian years) at a semi-major axis of 3.43 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 15.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.08 carries the world between 3.1556 AU at periapsis and 3.7044 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 140 K (-133°C / -207°F) and an incident flux of 0.06 S⊕ (~84 W/m²), surface water and volatile species on HD 290327 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 290327 is classified as a solar-type yellow star of spectral type G8 V with an effective photospheric temperature of 5,505 K, a radius of 0.95 R☉, a mass of 0.84 M☉, an estimated bolometric luminosity of 0.744 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.14 dex (metal-poor relative to the Sun). From Earth, HD 290327 shines at apparent V-band magnitude 8.99 (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 290327 |
| Spectral Type | G8 V |
| Effective Temp (Teff) | 5,505 K |
| Stellar Radius | 0.9500 R☉ |
| Stellar Mass | 0.8400 M☉ |
| Bolometric Luminosity | 0.744 L☉ |
| Metallicity [Fe/H] | -0.140 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.990 · G: 8.804 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.430000 AU |
| Orbital Period | 2443 days |
| Mean Orbital Velocity | 15.3 km/s |
| Orbital Eccentricity (e) | 0.08000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.81 g/cm³ (85.2 km/s vesc) |
| Insolation Flux | 0.0616 S⊕ (~84 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 184.100 LY (56.433 pc) |