HD 95338 b
Astrophysical Synthesis & Habitability Characterization
HD 95338 b is a confirmed sub-neptune exoplanet orbiting the star HD 95338, located approximately 120.7 light-years (36.99 parsecs) from the Solar System. First announced in 2020 by Las Campanas Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 4.272 Earth radii (0.38 Jupiter radii) and has a measured mass of 42.9 Earth masses (0.13 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.03 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 2.35 g⊕ (23.05 m/s²), and an escape velocity of 35.4 km/s.
In its orbital architecture around HD 95338, HD 95338 b completes one full revolution every 55.083 Earth days at a semi-major axis of 0.262 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 51.7 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.197 carries the world between 0.2104 AU at periapsis and 0.3136 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 443 K (+170°C / +338°F) and receiving 7.42 S⊕ (~10,099 W/m²), HD 95338 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 95338 is classified as an orange K-type star of spectral type K0.5 V with an effective photospheric temperature of 5,097 K, a radius of 0.868 R☉, a mass of 0.848 M☉, an estimated bolometric luminosity of 0.456 L☉. Stellar evolution modeling indicates an estimated stellar age of 9.5 Gyr and a metallicity of [Fe/H] = 0.08 dex (metal-rich relative to the Sun). From Earth, HD 95338 shines at apparent V-band magnitude 8.62 (accessible to binoculars and small amateur telescopes) in the Southern 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: Las Campanas Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 95338 |
| Spectral Type | K0.5 V |
| Effective Temp (Teff) | 5,097 K |
| Stellar Radius | 0.8680 R☉ |
| Stellar Mass | 0.8480 M☉ |
| Bolometric Luminosity | 0.456 L☉ |
| Metallicity [Fe/H] | 0.080 dex |
| Stellar Age | 9.500 Gyr |
| Apparent Magnitude | V: 8.620 · G: 8.382 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.262000 AU |
| Orbital Period | 55.083 days |
| Mean Orbital Velocity | 51.7 km/s |
| Orbital Eccentricity (e) | 0.19700 |
| Orbital Inclination (i) | 89.6540° |
| Mean Bulk Density | 3.03 g/cm³ (35.4 km/s vesc) |
| Insolation Flux | 7.4200 S⊕ (~10,099 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 120.700 LY (36.994 pc) |