HD 37124 b
Astrophysical Synthesis & Habitability Characterization
HD 37124 b is a confirmed gas giant exoplanet orbiting the star HD 37124, located approximately 103.3 light-years (31.66 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 14 Earth radii (1.25 Jupiter radii) and has a measured mass of 214.535 Earth masses (0.67 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.43 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 43.8 km/s.
In its orbital architecture around HD 37124, HD 37124 b completes one full revolution every 154.378 Earth days at a semi-major axis of 0.53364 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 37.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.054 carries the world between 0.5048 AU at periapsis and 0.5625 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 366 K (+93°C / +199°F) and receiving 2.71 S⊕ (~3,691 W/m²), HD 37124 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 37124 is classified as a solar-type yellow star of spectral type G4 V with an effective photospheric temperature of 5,699 K, a radius of 0.9492 R☉, a mass of 0.85 M☉, an estimated bolometric luminosity of 0.853 L☉. Stellar evolution modeling indicates an estimated stellar age of 4 Gyr and a metallicity of [Fe/H] = -0.44 dex (metal-poor relative to the Sun). From Earth, HD 37124 shines at apparent V-band magnitude 7.68 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 37124 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 37124 b sharing its stellar neighborhood alongside HD 37124 c, HD 37124 d.
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 37124 |
| Spectral Type | G4 V |
| Effective Temp (Teff) | 5,699 K |
| Stellar Radius | 0.9492 R☉ |
| Stellar Mass | 0.8500 M☉ |
| Bolometric Luminosity | 0.853 L☉ |
| Metallicity [Fe/H] | -0.440 dex |
| Stellar Age | 4.000 Gyr |
| Apparent Magnitude | V: 7.680 · G: 7.472 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.533640 AU |
| Orbital Period | 154.378 days |
| Mean Orbital Velocity | 37.6 km/s |
| Orbital Eccentricity (e) | 0.05400 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.43 g/cm³ (43.8 km/s vesc) |
| Insolation Flux | 2.7119 S⊕ (~3,691 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 103.300 LY (31.663 pc) |