HD 3167 c
Astrophysical Synthesis & Habitability Characterization
HD 3167 c is a confirmed sub-neptune exoplanet orbiting the star HD 3167, located approximately 154.2 light-years (47.29 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0986% across the stellar disk), this world measures 2.983 Earth radii and has a measured mass of 11.41 Earth masses. Combining its mass and radius yields a mean bulk density of 2.37 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.28 g⊕ (12.55 m/s²), and an escape velocity of 21.9 km/s.
In its orbital architecture around HD 3167, HD 3167 c completes one full revolution every 29.847 Earth days at a semi-major axis of 0.1794 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 65.4 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.04 (ranging from 0.1722 AU at periapsis to 0.1866 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 567 K (+294°C / +561°F) and receiving 16.90 S⊕ (~23,001 W/m²), HD 3167 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 3167 is classified as an orange K-type star of spectral type K0 V with an effective photospheric temperature of 5,338 K, a radius of 0.871 R☉, a mass of 0.864 M☉, an estimated bolometric luminosity of 0.553 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.4 Gyr and a metallicity of [Fe/H] = 0.037 dex (near-solar heavy-element abundance). From Earth, HD 3167 shines at apparent V-band magnitude 8.97 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 3167 system is a multi-planet architecture hosting 4 confirmed worlds, with HD 3167 c sharing its stellar neighborhood alongside HD 3167 b, HD 3167 d, HD 3167 e.
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: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 3167 |
| Spectral Type | K0 V |
| Effective Temp (Teff) | 5,338 K |
| Stellar Radius | 0.8710 R☉ |
| Stellar Mass | 0.8640 M☉ |
| Bolometric Luminosity | 0.553 L☉ |
| Metallicity [Fe/H] | 0.037 dex |
| Stellar Age | 8.400 Gyr |
| Apparent Magnitude | V: 8.970 · G: 8.762 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.179400 AU |
| Orbital Period | 29.847 days |
| Mean Orbital Velocity | 65.4 km/s |
| Orbital Eccentricity (e) | 0.04000 |
| Orbital Inclination (i) | 89.4330° |
| Mean Bulk Density | 2.37 g/cm³ (21.9 km/s vesc) |
| Insolation Flux | 16.9000 S⊕ (~23,001 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 154.200 LY (47.290 pc) |