HD 20794 f
Astrophysical Synthesis & Habitability Characterization
HD 20794 f is a confirmed sub-neptune exoplanet orbiting the star HD 20794, located approximately 19.6 light-years (6 parsecs) from the Solar System. First announced in 2025 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.28 Earth radii and has a measured mass of 5.82 Earth masses. Combining its mass and radius yields a mean bulk density of 2.71 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.9 km/s.
In its orbital architecture around HD 20794, HD 20794 f completes one full revolution every 647.6 Earth days (1.77Julian years) at a semi-major axis of 1.3541 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 22.7 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.45, swinging from 0.7448 AU at periapsis out to 1.9634 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.280 R⊕, HD 20794 f exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star HD 20794 is classified as a solar-type yellow star of spectral type G6 V with an effective photospheric temperature of 5,368 K, a radius of 0.93 R☉, a mass of 0.79 M☉, an estimated bolometric luminosity of 0.644 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.76 Gyr and a metallicity of [Fe/H] = -0.42 dex (metal-poor relative to the Sun). From Earth, HD 20794 shines at apparent V-band magnitude 4.26 (visible to the unaided human eye under dark skies) in the Southern celestial hemisphere. The HD 20794 system is a multi-planet architecture hosting 4 confirmed worlds, with HD 20794 f sharing its stellar neighborhood alongside HD 20794 b, HD 20794 d, HD 20794 e.
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 20794 |
| Spectral Type | G6 V |
| Effective Temp (Teff) | 5,368 K |
| Stellar Radius | 0.9300 R☉ |
| Stellar Mass | 0.7900 M☉ |
| Bolometric Luminosity | 0.644 L☉ |
| Metallicity [Fe/H] | -0.420 dex |
| Stellar Age | 5.760 Gyr |
| Apparent Magnitude | V: 4.260 · G: 4.066 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.354100 AU |
| Orbital Period | 647.6 days |
| Mean Orbital Velocity | 22.7 km/s |
| Orbital Eccentricity (e) | 0.45000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.71 g/cm³ (17.9 km/s vesc) |
| Insolation Flux | 0.3746 S⊕ (~510 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 19.600 LY (6.003 pc) |