HD 89307 b
Astrophysical Synthesis & Habitability Characterization
HD 89307 b is a confirmed gas giant exoplanet orbiting the star HD 89307, located approximately 104.4 light-years (32.01 parsecs) from the Solar System. First announced in 2009 by Lick 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 642.013 Earth masses (2.02 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.47 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.58 g⊕ (35.11 m/s²), and an escape velocity of 77.4 km/s.
In its orbital architecture around HD 89307, HD 89307 b completes one full revolution every 2166 Earth days (5.93Julian years) at a semi-major axis of 3.27 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 16.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.2 carries the world between 2.616 AU at periapsis and 3.924 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 167 K (-106°C / -159°F) and an incident flux of 0.13 S⊕ (~172 W/m²), surface water and volatile species on HD 89307 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 89307 is classified as a solar-type yellow star of spectral type G0 V with an effective photospheric temperature of 5,955 K, a radius of 1.1 R☉, a mass of 1.27 M☉, an estimated bolometric luminosity of 1.365 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.31 Gyr and a metallicity of [Fe/H] = -0.13 dex (metal-poor relative to the Sun). From Earth, HD 89307 shines at apparent V-band magnitude 7.026 (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: Lick Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 89307 |
| Spectral Type | G0 V |
| Effective Temp (Teff) | 5,955 K |
| Stellar Radius | 1.1000 R☉ |
| Stellar Mass | 1.2700 M☉ |
| Bolometric Luminosity | 1.365 L☉ |
| Metallicity [Fe/H] | -0.130 dex |
| Stellar Age | 2.310 Gyr |
| Apparent Magnitude | V: 7.026 · G: 6.868 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.270000 AU |
| Orbital Period | 2166 days |
| Mean Orbital Velocity | 16.4 km/s |
| Orbital Eccentricity (e) | 0.20000 |
| Orbital Inclination (i) | 72.0000° |
| Mean Bulk Density | 1.47 g/cm³ (77.4 km/s vesc) |
| Insolation Flux | 0.1265 S⊕ (~172 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 104.400 LY (32.010 pc) |