HD 50554 d
Astrophysical Synthesis & Habitability Characterization
HD 50554 d is a confirmed super-earth exoplanet orbiting the star HD 50554, located approximately 101.7 light-years (31.17 parsecs) from the Solar System. First announced in 2026 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0127% across the stellar disk), this world measures 1.41 Earth radii and has a measured mass of 10.4 Earth masses. Combining its mass and radius yields a mean bulk density of 20.46 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 5.23 g⊕ (51.29 m/s²), and an escape velocity of 30.4 km/s.
In its orbital architecture around HD 50554, HD 50554 d completes one full revolution every 28.069 Earth days at a semi-major axis of 0.1831 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 71 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 651 K (+378°C / +712°F) and receiving 42.48 S⊕ (~57,809 W/m²), HD 50554 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 50554 is classified as a warm F-type star of spectral type F8 V with an effective photospheric temperature of 5,968 K, a radius of 1.146 R☉, a mass of 1.04 M☉, an estimated bolometric luminosity of 1.495 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 d sharing its stellar neighborhood alongside HD 50554 c, HD 50554 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: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 50554 |
| Spectral Type | F8 V |
| Effective Temp (Teff) | 5,968 K |
| Stellar Radius | 1.1460 R☉ |
| Stellar Mass | 1.0400 M☉ |
| Bolometric Luminosity | 1.495 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) | 0.183100 AU |
| Orbital Period | 28.069 days |
| Mean Orbital Velocity | 71 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 20.46 g/cm³ (30.4 km/s vesc) |
| Insolation Flux | 42.4756 S⊕ (~57,809 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 101.700 LY (31.166 pc) |