HD 564 b
Astrophysical Synthesis & Habitability Characterization
HD 564 b is a confirmed gas giant exoplanet orbiting the star HD 564, located approximately 166.9 light-years (51.17 parsecs) from the Solar System. First announced in 2014 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 104.88 Earth masses (0.33 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.3 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.67 g⊕ (6.57 m/s²), and an escape velocity of 32.4 km/s.
In its orbital architecture around HD 564, HD 564 b completes one full revolution every 492.3 Earth days (1.35Julian years) at a semi-major axis of 1.2 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 26.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.096 carries the world between 1.0848 AU at periapsis and 1.3152 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.500 R⊕, HD 564 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 564 is classified as a solar-type yellow star of spectral type G2/G3 V with an effective photospheric temperature of 5,902 K, a radius of 1.01 R☉, a mass of 0.961 M☉, an estimated bolometric luminosity of 1.111 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.5 Gyr and a metallicity of [Fe/H] = -0.2 dex (metal-poor relative to the Sun). From Earth, HD 564 shines at apparent V-band magnitude 8.32 (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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 564 |
| Spectral Type | G2/G3 V |
| Effective Temp (Teff) | 5,902 K |
| Stellar Radius | 1.0100 R☉ |
| Stellar Mass | 0.9610 M☉ |
| Bolometric Luminosity | 1.111 L☉ |
| Metallicity [Fe/H] | -0.200 dex |
| Stellar Age | 5.500 Gyr |
| Apparent Magnitude | V: 8.320 · G: 8.171 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.200000 AU |
| Orbital Period | 492.3 days |
| Mean Orbital Velocity | 26.5 km/s |
| Orbital Eccentricity (e) | 0.09600 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.3 g/cm³ (32.4 km/s vesc) |
| Insolation Flux | 0.7254 S⊕ (~987 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 166.900 LY (51.166 pc) |