HD 19994 b
Astrophysical Synthesis & Habitability Characterization
HD 19994 b is a confirmed gas giant exoplanet orbiting the star HD 19994, located approximately 73.5 light-years (22.52 parsecs) from the Solar System. First announced in 2003 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.6 Earth radii (1.21 Jupiter radii) and has a measured mass of 435.41 Earth masses (1.37 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.95 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.35 g⊕ (23.05 m/s²), and an escape velocity of 63.3 km/s.
In its orbital architecture around HD 19994, HD 19994 b completes one full revolution every 466.2 Earth days (1.28Julian years) at a semi-major axis of 1.305 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 30.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.063 carries the world between 1.2228 AU at periapsis and 1.3872 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.600 R⊕, HD 19994 b 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 19994 is classified as a warm F-type star of spectral type F8 V with an effective photospheric temperature of 6,188 K, a radius of 1.7965 R☉, a mass of 1.365 M☉, an estimated bolometric luminosity of 4.246 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.4 Gyr and a metallicity of [Fe/H] = 0.27 dex (metal-rich relative to the Sun). From Earth, HD 19994 shines at apparent V-band magnitude 5.063 (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 19994 |
| Spectral Type | F8 V |
| Effective Temp (Teff) | 6,188 K |
| Stellar Radius | 1.7965 R☉ |
| Stellar Mass | 1.3650 M☉ |
| Bolometric Luminosity | 4.246 L☉ |
| Metallicity [Fe/H] | 0.270 dex |
| Stellar Age | 2.400 Gyr |
| Apparent Magnitude | V: 5.063 · G: 4.930 |
| System Architecture | 3 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.305000 AU |
| Orbital Period | 466.2 days |
| Mean Orbital Velocity | 30.5 km/s |
| Orbital Eccentricity (e) | 0.06300 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.95 g/cm³ (63.3 km/s vesc) |
| Insolation Flux | 2.2324 S⊕ (~3,038 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 73.500 LY (22.524 pc) |