HIP 54373 b
Astrophysical Synthesis & Habitability Characterization
HIP 54373 b is a confirmed sub-neptune exoplanet orbiting the star HIP 54373, located approximately 61 light-years (18.72 parsecs) from the Solar System. First announced in 2019 by Las Campanas Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.87 Earth radii and has a measured mass of 8.62 Earth masses. Combining its mass and radius yields a mean bulk density of 2.01 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.4 km/s.
In its orbital architecture around HIP 54373, HIP 54373 b completes one full revolution every 7.76 Earth days at a semi-major axis of 0.063 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 88.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.2 carries the world between 0.0504 AU at periapsis and 0.0756 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 581 K (+308°C / +586°F) and receiving 15.10 S⊕ (~20,549 W/m²), HIP 54373 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HIP 54373 is classified as an orange K-type star of spectral type K5 V with an effective photospheric temperature of 4,021 K, a radius of 0.565 R☉, a mass of 0.57 M☉, an estimated bolometric luminosity of 0.075 L☉. From Earth, HIP 54373 shines at apparent V-band magnitude 10.38 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The HIP 54373 system is a multi-planet architecture hosting 2 confirmed worlds, with HIP 54373 b sharing its stellar neighborhood alongside HIP 54373 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: Las Campanas Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HIP 54373 |
| Spectral Type | K5 V |
| Effective Temp (Teff) | 4,021 K |
| Stellar Radius | 0.5650 R☉ |
| Stellar Mass | 0.5700 M☉ |
| Bolometric Luminosity | 0.075 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 10.380 · G: 9.641 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.063000 AU |
| Orbital Period | 7.76 days |
| Mean Orbital Velocity | 88.3 km/s |
| Orbital Eccentricity (e) | 0.20000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.01 g/cm³ (19.4 km/s vesc) |
| Insolation Flux | 15.0984 S⊕ (~20,549 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 61.000 LY (18.717 pc) |