HD 39194 c
Astrophysical Synthesis & Habitability Characterization
HD 39194 c is a confirmed sub-neptune exoplanet orbiting the star HD 39194, located approximately 86.1 light-years (26.41 parsecs) from the Solar System. First announced in 2021 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.65 Earth radii and has a measured mass of 7.49 Earth masses. Combining its mass and radius yields a mean bulk density of 2.22 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.07 g⊕ (10.49 m/s²), and an escape velocity of 18.8 km/s.
In its orbital architecture around HD 39194, HD 39194 c completes one full revolution every 14.031 Earth days at a semi-major axis of 0.1083 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 84 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.078 carries the world between 0.0999 AU at periapsis and 0.1167 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 675 K (+402°C / +756°F) and receiving 33.25 S⊕ (~45,255 W/m²), HD 39194 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 39194 is classified as an orange K-type star of spectral type K0 V with an effective photospheric temperature of 5,205 K, a radius of 0.7837 R☉, a mass of 0.86 M☉, an estimated bolometric luminosity of 0.404 L☉. Stellar evolution modeling indicates an estimated stellar age of 10 Gyr and a metallicity of [Fe/H] = -0.61 dex (metal-poor relative to the Sun). From Earth, HD 39194 shines at apparent V-band magnitude 8.09 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 39194 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 39194 c sharing its stellar neighborhood alongside HD 39194 b, HD 39194 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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 39194 |
| Spectral Type | K0 V |
| Effective Temp (Teff) | 5,205 K |
| Stellar Radius | 0.7837 R☉ |
| Stellar Mass | 0.8600 M☉ |
| Bolometric Luminosity | 0.404 L☉ |
| Metallicity [Fe/H] | -0.610 dex |
| Stellar Age | 10.000 Gyr |
| Apparent Magnitude | V: 8.090 · G: 7.852 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.108300 AU |
| Orbital Period | 14.031 days |
| Mean Orbital Velocity | 84 km/s |
| Orbital Eccentricity (e) | 0.07800 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.22 g/cm³ (18.8 km/s vesc) |
| Insolation Flux | 33.2512 S⊕ (~45,255 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 86.100 LY (26.413 pc) |