HD 219077 b
Astrophysical Synthesis & Habitability Characterization
HD 219077 b is a confirmed gas giant exoplanet orbiting the star HD 219077, located approximately 95.2 light-years (29.19 parsecs) from the Solar System. First announced in 2012 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.5 Earth radii (1.12 Jupiter radii) and has a measured mass of 3057.509 Earth masses (9.62 Jupiter masses). Combining its mass and radius yields a mean bulk density of 8.63 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 19.57 g⊕ (191.92 m/s²), and an escape velocity of 174.9 km/s.
In its orbital architecture around HD 219077, HD 219077 b completes one full revolution every 5478.689 Earth days (15Julian years) at a semi-major axis of 5.935 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 11.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.768, swinging from 1.3769 AU at periapsis out to 10.4931 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 147 K (-126°C / -195°F) and an incident flux of 0.08 S⊕ (~103 W/m²), surface water and volatile species on HD 219077 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 219077 is classified as a solar-type yellow star of spectral type G8 V+ with an effective photospheric temperature of 5,362 K, a radius of 1.91 R☉, a mass of 0.92 M☉, an estimated bolometric luminosity of 2.706 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.9 Gyr and a metallicity of [Fe/H] = -0.13 dex (metal-poor relative to the Sun). From Earth, HD 219077 shines at apparent V-band magnitude 6.12 (visible to the unaided human eye under dark skies) 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 219077 |
| Spectral Type | G8 V+ |
| Effective Temp (Teff) | 5,362 K |
| Stellar Radius | 1.9100 R☉ |
| Stellar Mass | 0.9200 M☉ |
| Bolometric Luminosity | 2.706 L☉ |
| Metallicity [Fe/H] | -0.130 dex |
| Stellar Age | 8.900 Gyr |
| Apparent Magnitude | V: 6.120 · G: 5.916 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 5.935000 AU |
| Orbital Period | 5478.689 days |
| Mean Orbital Velocity | 11.8 km/s |
| Orbital Eccentricity (e) | 0.76800 |
| Orbital Inclination (i) | 90.1780° |
| Mean Bulk Density | 8.63 g/cm³ (174.9 km/s vesc) |
| Insolation Flux | 0.0755 S⊕ (~103 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 95.200 LY (29.186 pc) |