BD+45 564 b
Astrophysical Synthesis & Habitability Characterization
BD+45 564 b is a confirmed gas giant exoplanet orbiting the star BD+45 564, located approximately 174.9 light-years (53.62 parsecs) from the Solar System. First announced in 2021 by Haute-Provence 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 432.247 Earth masses (1.36 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 2.34 g⊕ (22.95 m/s²), and an escape velocity of 63.1 km/s.
In its orbital architecture around BD+45 564, BD+45 564 b completes one full revolution every 307.88 Earth days at a semi-major axis of 0.83 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 29.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.12 carries the world between 0.7304 AU at periapsis and 0.9296 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.600 R⊕, BD+45 564 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 BD+45 564 is classified as an orange K-type star of spectral type K1 with an effective photospheric temperature of 5,004 K, a radius of 0.8131 R☉, a mass of 0.81 M☉, an estimated bolometric luminosity of 0.372 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.09 dex (near-solar heavy-element abundance). From Earth, BD+45 564 shines at apparent V-band magnitude 9.67 (accessible to binoculars and small amateur telescopes) in the Northern 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: Haute-Provence Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | BD+45 564 |
| Spectral Type | K1 |
| Effective Temp (Teff) | 5,004 K |
| Stellar Radius | 0.8131 R☉ |
| Stellar Mass | 0.8100 M☉ |
| Bolometric Luminosity | 0.372 L☉ |
| Metallicity [Fe/H] | -0.090 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.670 · G: 9.413 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.830000 AU |
| Orbital Period | 307.88 days |
| Mean Orbital Velocity | 29.3 km/s |
| Orbital Eccentricity (e) | 0.12000 |
| Orbital Inclination (i) | 2.5790° |
| Mean Bulk Density | 0.95 g/cm³ (63.1 km/s vesc) |
| Insolation Flux | 0.5790 S⊕ (~788 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 174.900 LY (53.622 pc) |