HD 38283 b
Astrophysical Synthesis & Habitability Characterization
HD 38283 b is a confirmed gas giant exoplanet orbiting the star HD 38283, located approximately 124.1 light-years (38.06 parsecs) from the Solar System. First announced in 2010 by Anglo-Australian Telescope using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 14 Earth radii (1.25 Jupiter radii) and has a measured mass of 127.132 Earth masses (0.4 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.26 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.65 g⊕ (6.37 m/s²), and an escape velocity of 33.7 km/s.
In its orbital architecture around HD 38283, HD 38283 b completes one full revolution every 363.2 Earth days at a semi-major axis of 1.02 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 30.6 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.41, swinging from 0.6018 AU at periapsis out to 1.4382 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 14.000 R⊕, HD 38283 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star HD 38283 is classified as a warm F-type star of spectral type F9.5 V with an effective photospheric temperature of 5,981 K, a radius of 1.49 R☉, a mass of 1.37 M☉, an estimated bolometric luminosity of 2.549 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.2 Gyr and a metallicity of [Fe/H] = -0.18 dex (metal-poor relative to the Sun). From Earth, HD 38283 shines at apparent V-band magnitude 6.69 (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: Anglo-Australian Telescope · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 38283 |
| Spectral Type | F9.5 V |
| Effective Temp (Teff) | 5,981 K |
| Stellar Radius | 1.4900 R☉ |
| Stellar Mass | 1.3700 M☉ |
| Bolometric Luminosity | 2.549 L☉ |
| Metallicity [Fe/H] | -0.180 dex |
| Stellar Age | 6.200 Gyr |
| Apparent Magnitude | V: 6.690 · G: 6.544 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.020000 AU |
| Orbital Period | 363.2 days |
| Mean Orbital Velocity | 30.6 km/s |
| Orbital Eccentricity (e) | 0.41000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.26 g/cm³ (33.7 km/s vesc) |
| Insolation Flux | 2.4745 S⊕ (~3,368 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 124.100 LY (38.062 pc) |