HD 76920 b
Astrophysical Synthesis & Habitability Characterization
HD 76920 b is a confirmed gas giant exoplanet orbiting the star HD 76920, located approximately 600.2 light-years (184.03 parsecs) from the Solar System. First announced in 2017 by Multiple Observatories 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 994.803 Earth masses (3.13 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.44 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 5.8 g⊕ (56.88 m/s²), and an escape velocity of 97.5 km/s.
In its orbital architecture around HD 76920, HD 76920 b completes one full revolution every 415.891 Earth days (1.14Julian years) at a semi-major axis of 1.091 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 28.5 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.8782, swinging from 0.1329 AU at periapsis out to 2.0491 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 621 K (+348°C / +658°F) and receiving 24.78 S⊕ (~33,731 W/m²), HD 76920 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 76920 is classified as an orange K-type star of spectral type K1 III with an effective photospheric temperature of 4,664 K, a radius of 8.33 R☉, a mass of 1 M☉, an estimated bolometric luminosity of 29.459 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.2 Gyr and a metallicity of [Fe/H] = -0.19 dex (metal-poor relative to the Sun). From Earth, HD 76920 shines at apparent V-band magnitude 7.83 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 76920 |
| Spectral Type | K1 III |
| Effective Temp (Teff) | 4,664 K |
| Stellar Radius | 8.3300 R☉ |
| Stellar Mass | 1.0000 M☉ |
| Bolometric Luminosity | 29.459 L☉ |
| Metallicity [Fe/H] | -0.190 dex |
| Stellar Age | 5.200 Gyr |
| Apparent Magnitude | V: 7.830 · G: 7.514 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.091000 AU |
| Orbital Period | 415.891 days |
| Mean Orbital Velocity | 28.5 km/s |
| Orbital Eccentricity (e) | 0.87820 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.44 g/cm³ (97.5 km/s vesc) |
| Insolation Flux | 24.7841 S⊕ (~33,731 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 600.200 LY (184.031 pc) |