HD 49674 b
Astrophysical Synthesis & Habitability Characterization
HD 49674 b is a confirmed gas giant exoplanet orbiting the star HD 49674, located approximately 140.4 light-years (43.04 parsecs) from the Solar System. First announced in 2002 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 6.2 Earth radii (0.55 Jupiter radii) and has a measured mass of 31.783 Earth masses (0.1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.74 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.83 g⊕ (8.14 m/s²), and an escape velocity of 25.3 km/s.
In its orbital architecture around HD 49674, HD 49674 b completes one full revolution every 4.947 Earth days at a semi-major axis of 0.06 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 131.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.09 carries the world between 0.0546 AU at periapsis and 0.0654 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1114 K (+841°C / +1546°F) and receiving 264.29 S⊕ (~359,695 W/m²), HD 49674 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 49674 is classified as a solar-type yellow star of spectral type G5 V with an effective photospheric temperature of 5,602 K, a radius of 1.02 R☉, a mass of 1.03 M☉, an estimated bolometric luminosity of 0.919 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.62 Gyr and a metallicity of [Fe/H] = 0.32 dex (metal-rich relative to the Sun). From Earth, HD 49674 shines at apparent V-band magnitude 8.1 (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 49674 |
| Spectral Type | G5 V |
| Effective Temp (Teff) | 5,602 K |
| Stellar Radius | 1.0200 R☉ |
| Stellar Mass | 1.0300 M☉ |
| Bolometric Luminosity | 0.919 L☉ |
| Metallicity [Fe/H] | 0.320 dex |
| Stellar Age | 3.620 Gyr |
| Apparent Magnitude | V: 8.100 · G: 7.918 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.060000 AU |
| Orbital Period | 4.947 days |
| Mean Orbital Velocity | 131.9 km/s |
| Orbital Eccentricity (e) | 0.09000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.74 g/cm³ (25.3 km/s vesc) |
| Insolation Flux | 264.2871 S⊕ (~359,695 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 140.400 LY (43.040 pc) |