HD 4113 b
Astrophysical Synthesis & Habitability Characterization
HD 4113 b is a confirmed gas giant exoplanet orbiting the star HD 4113, located approximately 136.6 light-years (41.87 parsecs) from the Solar System. First announced in 2007 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.5 Earth radii (1.2 Jupiter radii) and has a measured mass of 541.262 Earth masses (1.7 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.21 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.97 g⊕ (29.13 m/s²), and an escape velocity of 70.8 km/s.
In its orbital architecture around HD 4113, HD 4113 b completes one full revolution every 526.524 Earth days (1.44Julian years) at a semi-major axis of 1.28 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 26.4 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.899, swinging from 0.1293 AU at periapsis out to 2.4307 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.500 R⊕, HD 4113 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 4113 is classified as a solar-type yellow star of spectral type G5 V with an effective photospheric temperature of 5,688 K, a radius of 1.0775 R☉, a mass of 1.008 M☉, an estimated bolometric luminosity of 1.09 L☉. Stellar evolution modeling indicates an estimated stellar age of 5 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, HD 4113 shines at apparent V-band magnitude 7.88 (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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 4113 |
| Spectral Type | G5 V |
| Effective Temp (Teff) | 5,688 K |
| Stellar Radius | 1.0775 R☉ |
| Stellar Mass | 1.0080 M☉ |
| Bolometric Luminosity | 1.09 L☉ |
| Metallicity [Fe/H] | 0.200 dex |
| Stellar Age | 5.000 Gyr |
| Apparent Magnitude | V: 7.880 · G: 7.711 |
| System Architecture | 3 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.280000 AU |
| Orbital Period | 526.524 days |
| Mean Orbital Velocity | 26.4 km/s |
| Orbital Eccentricity (e) | 0.89900 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.21 g/cm³ (70.8 km/s vesc) |
| Insolation Flux | 0.7440 S⊕ (~1,013 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 136.600 LY (41.873 pc) |