HD 5319 c
Astrophysical Synthesis & Habitability Characterization
HD 5319 c is a confirmed gas giant exoplanet orbiting the star HD 5319, located approximately 396 light-years (121.41 parsecs) from the Solar System. First announced in 2014 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.8 Earth radii (1.23 Jupiter radii) and has a measured mass of 334.675 Earth masses (1.05 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.7 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.76 g⊕ (17.26 m/s²), and an escape velocity of 55.1 km/s.
In its orbital architecture around HD 5319, HD 5319 c completes one full revolution every 872.2 Earth days (2.39Julian years) at a semi-major axis of 1.93 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 24.1 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.183 carries the world between 1.5768 AU at periapsis and 2.2832 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.800 R⊕, HD 5319 c 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 5319 is classified as a solar-type yellow star of spectral type G5 with an effective photospheric temperature of 4,871 K, a radius of 4.06 R☉, a mass of 1.27 M☉, an estimated bolometric luminosity of 8.326 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.1 Gyr and a metallicity of [Fe/H] = 0.15 dex (metal-rich relative to the Sun). From Earth, HD 5319 shines at apparent V-band magnitude 8.05 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 5319 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 5319 c sharing its stellar neighborhood alongside HD 5319 b.
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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 5319 |
| Spectral Type | G5 |
| Effective Temp (Teff) | 4,871 K |
| Stellar Radius | 4.0600 R☉ |
| Stellar Mass | 1.2700 M☉ |
| Bolometric Luminosity | 8.326 L☉ |
| Metallicity [Fe/H] | 0.150 dex |
| Stellar Age | 3.100 Gyr |
| Apparent Magnitude | V: 8.050 · G: 7.772 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.930000 AU |
| Orbital Period | 872.2 days |
| Mean Orbital Velocity | 24.1 km/s |
| Orbital Eccentricity (e) | 0.18300 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.7 g/cm³ (55.1 km/s vesc) |
| Insolation Flux | 2.1721 S⊕ (~2,956 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 396.000 LY (121.405 pc) |