HD 50554 b
Astrophysical Synthesis & Habitability Characterization
HD 50554 b is a confirmed gas giant exoplanet orbiting the star HD 50554, located approximately 101.7 light-years (31.17 parsecs) from the Solar System. First announced in 2002 by Lick Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.8 Earth radii (1.14 Jupiter radii) and has a measured mass of 1859.296 Earth masses (5.85 Jupiter masses). Combining its mass and radius yields a mean bulk density of 4.89 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 11.35 g⊕ (111.31 m/s²), and an escape velocity of 134.8 km/s.
In its orbital architecture around HD 50554, HD 50554 b completes one full revolution every 1240 Earth days (3.39Julian years) at a semi-major axis of 2.339 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 20.5 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.482, swinging from 1.2116 AU at periapsis out to 3.4664 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.800 R⊕, HD 50554 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 50554 is classified as a warm F-type star of spectral type F8 V with an effective photospheric temperature of 6,050 K, a radius of 1.02 R☉, a mass of 1.1 M☉, an estimated bolometric luminosity of 1.251 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.16 Gyr and a metallicity of [Fe/H] = 0.02 dex (near-solar heavy-element abundance). From Earth, HD 50554 shines at apparent V-band magnitude 6.856 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 50554 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 50554 b sharing its stellar neighborhood alongside HD 50554 c, HD 50554 d.
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: Lick Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 50554 |
| Spectral Type | F8 V |
| Effective Temp (Teff) | 6,050 K |
| Stellar Radius | 1.0200 R☉ |
| Stellar Mass | 1.1000 M☉ |
| Bolometric Luminosity | 1.251 L☉ |
| Metallicity [Fe/H] | 0.020 dex |
| Stellar Age | 2.160 Gyr |
| Apparent Magnitude | V: 6.856 · G: 6.698 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.339000 AU |
| Orbital Period | 1240 days |
| Mean Orbital Velocity | 20.5 km/s |
| Orbital Eccentricity (e) | 0.48200 |
| Orbital Inclination (i) | 61.0000° |
| Mean Bulk Density | 4.89 g/cm³ (134.8 km/s vesc) |
| Insolation Flux | 0.2738 S⊕ (~373 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 101.700 LY (31.166 pc) |