HD 37124 c
Astrophysical Synthesis & Habitability Characterization
HD 37124 c 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 14.1 Earth radii (1.26 Jupiter radii) and has a measured mass of 207.225 Earth masses (0.65 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.41 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.04 g⊕ (10.2 m/s²), and an escape velocity of 42.9 km/s.
In its orbital architecture around HD 37124, HD 37124 c completes one full revolution every 885.5 Earth days (2.42Julian years) at a semi-major axis of 1.71 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 21 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.125 carries the world between 1.4962 AU at periapsis and 1.9238 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 14.100 R⊕, HD 37124 c 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 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 c sharing its stellar neighborhood alongside HD 37124 b, 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) | 1.710000 AU |
| Orbital Period | 885.5 days |
| Mean Orbital Velocity | 21 km/s |
| Orbital Eccentricity (e) | 0.12500 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.41 g/cm³ (42.9 km/s vesc) |
| Insolation Flux | 0.2641 S⊕ (~359 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 103.300 LY (31.663 pc) |