HD 45184 b
Astrophysical Synthesis & Habitability Characterization
HD 45184 b is a confirmed sub-neptune exoplanet orbiting the star HD 45184, located approximately 71.6 light-years (21.95 parsecs) from the Solar System. First announced in 2019 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 3.52 Earth radii (0.31 Jupiter radii) and has a measured mass of 12.19 Earth masses. Combining its mass and radius yields a mean bulk density of 1.54 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.98 g⊕ (9.61 m/s²), and an escape velocity of 20.8 km/s.
In its orbital architecture around HD 45184, HD 45184 b completes one full revolution every 5.885 Earth days at a semi-major axis of 0.0644 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 119 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.07 carries the world between 0.0599 AU at periapsis and 0.0689 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1156 K (+883°C / +1621°F) and receiving 272.46 S⊕ (~370,821 W/m²), HD 45184 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 45184 is classified as a solar-type yellow star of spectral type G1.5 V with an effective photospheric temperature of 5,869 K, a radius of 1.0751 R☉, a mass of 1.03 M☉, an estimated bolometric luminosity of 1.23 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.8 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, HD 45184 shines at apparent V-band magnitude 6.383 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 45184 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 45184 b sharing its stellar neighborhood alongside HD 45184 c.
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 45184 |
| Spectral Type | G1.5 V |
| Effective Temp (Teff) | 5,869 K |
| Stellar Radius | 1.0751 R☉ |
| Stellar Mass | 1.0300 M☉ |
| Bolometric Luminosity | 1.23 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 6.800 Gyr |
| Apparent Magnitude | V: 6.383 · G: 6.210 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.064400 AU |
| Orbital Period | 5.885 days |
| Mean Orbital Velocity | 119 km/s |
| Orbital Eccentricity (e) | 0.07000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.54 g/cm³ (20.8 km/s vesc) |
| Insolation Flux | 272.4625 S⊕ (~370,821 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 71.600 LY (21.953 pc) |