HD 46375 b
Astrophysical Synthesis & Habitability Characterization
HD 46375 b is a confirmed gas giant exoplanet orbiting the star HD 46375, located approximately 96.4 light-years (29.55 parsecs) from the Solar System. First announced in 2000 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 10 Earth radii (0.89 Jupiter radii) and has a measured mass of 71.8 Earth masses (0.23 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.4 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.72 g⊕ (7.06 m/s²), and an escape velocity of 30 km/s.
In its orbital architecture around HD 46375, HD 46375 b completes one full revolution every 3.024 Earth days at a semi-major axis of 0.0398 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 143.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.063 carries the world between 0.0373 AU at periapsis and 0.0423 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1221 K (+948°C / +1738°F) and receiving 359.10 S⊕ (~488,734 W/m²), HD 46375 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 46375 is classified as an orange K-type star of spectral type K1 IV-V with an effective photospheric temperature of 5,285 K, a radius of 0.9142 R☉, a mass of 0.92 M☉, an estimated bolometric luminosity of 0.585 L☉. Stellar evolution modeling indicates an estimated stellar age of 9 Gyr and a metallicity of [Fe/H] = 0.24 dex (metal-rich relative to the Sun). From Earth, HD 46375 shines at apparent V-band magnitude 7.91 (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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 46375 |
| Spectral Type | K1 IV-V |
| Effective Temp (Teff) | 5,285 K |
| Stellar Radius | 0.9142 R☉ |
| Stellar Mass | 0.9200 M☉ |
| Bolometric Luminosity | 0.585 L☉ |
| Metallicity [Fe/H] | 0.240 dex |
| Stellar Age | 9.000 Gyr |
| Apparent Magnitude | V: 7.910 · G: 7.695 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.039800 AU |
| Orbital Period | 3.024 days |
| Mean Orbital Velocity | 143.2 km/s |
| Orbital Eccentricity (e) | 0.06300 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.4 g/cm³ (30 km/s vesc) |
| Insolation Flux | 359.0994 S⊕ (~488,734 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 96.400 LY (29.553 pc) |