HD 192310 c
Astrophysical Synthesis & Habitability Characterization
HD 192310 c is a confirmed sub-neptune exoplanet orbiting the star HD 192310, located approximately 28.7 light-years (8.8 parsecs) from the Solar System. First announced in 2011 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 5.25 Earth radii (0.47 Jupiter radii) and has a measured mass of 24 Earth masses. Combining its mass and radius yields a mean bulk density of 0.91 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.87 g⊕ (8.53 m/s²), and an escape velocity of 23.9 km/s.
In its orbital architecture around HD 192310, HD 192310 c completes one full revolution every 525.8 Earth days (1.44Julian years) at a semi-major axis of 1.18 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 24.4 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.32, swinging from 0.8024 AU at periapsis out to 1.5576 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 5.250 R⊕, HD 192310 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 192310 is classified as an orange K-type star of spectral type K3V with an effective photospheric temperature of 5,166 K, a radius of 0.8579 R☉, a mass of 0.8 M☉, an estimated bolometric luminosity of 0.47 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.81 Gyr and a metallicity of [Fe/H] = -0.04 dex (near-solar heavy-element abundance). From Earth, HD 192310 shines at apparent V-band magnitude 5.73 (visible to the unaided human eye under dark skies) in the Southern celestial hemisphere. The HD 192310 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 192310 c sharing its stellar neighborhood alongside HD 192310 b.
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 192310 |
| Spectral Type | K3V |
| Effective Temp (Teff) | 5,166 K |
| Stellar Radius | 0.8579 R☉ |
| Stellar Mass | 0.8000 M☉ |
| Bolometric Luminosity | 0.47 L☉ |
| Metallicity [Fe/H] | -0.040 dex |
| Stellar Age | 7.810 Gyr |
| Apparent Magnitude | V: 5.730 · G: 5.477 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.180000 AU |
| Orbital Period | 525.8 days |
| Mean Orbital Velocity | 24.4 km/s |
| Orbital Eccentricity (e) | 0.32000 |
| Orbital Inclination (i) | 90.0000° |
| Mean Bulk Density | 0.91 g/cm³ (23.9 km/s vesc) |
| Insolation Flux | 0.2765 S⊕ (~376 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 28.700 LY (8.797 pc) |