HD 190360 c
Astrophysical Synthesis & Habitability Characterization
HD 190360 c is a confirmed sub-neptune exoplanet orbiting the star HD 190360, located approximately 52.2 light-years (16.01 parsecs) from the Solar System. First announced in 2005 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 5.53 Earth radii (0.49 Jupiter radii) and has a measured mass of 26.2 Earth masses. Combining its mass and radius yields a mean bulk density of 0.85 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.86 g⊕ (8.43 m/s²), and an escape velocity of 24.3 km/s.
In its orbital architecture around HD 190360, HD 190360 c completes one full revolution every 17.116 Earth days at a semi-major axis of 0.1298 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 82.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.163 carries the world between 0.1086 AU at periapsis and 0.151 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 795 K (+522°C / +972°F) and receiving 69.17 S⊕ (~94,141 W/m²), HD 190360 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 190360 is classified as a solar-type yellow star of spectral type G7 IV-V with an effective photospheric temperature of 5,560 K, a radius of 1.14 R☉, a mass of 0.996 M☉, an estimated bolometric luminosity of 1.114 L☉. Stellar evolution modeling indicates an estimated stellar age of 11.3 Gyr and a metallicity of [Fe/H] = 0.26 dex (metal-rich relative to the Sun). From Earth, HD 190360 shines at apparent V-band magnitude 5.738 (visible to the unaided human eye under dark skies) in the Northern celestial hemisphere. The HD 190360 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 190360 c sharing its stellar neighborhood alongside HD 190360 d, HD 190360 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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 190360 |
| Spectral Type | G7 IV-V |
| Effective Temp (Teff) | 5,560 K |
| Stellar Radius | 1.1400 R☉ |
| Stellar Mass | 0.9960 M☉ |
| Bolometric Luminosity | 1.114 L☉ |
| Metallicity [Fe/H] | 0.260 dex |
| Stellar Age | 11.300 Gyr |
| Apparent Magnitude | V: 5.738 · G: 5.554 |
| System Architecture | 2 Stars, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.129800 AU |
| Orbital Period | 17.116 days |
| Mean Orbital Velocity | 82.5 km/s |
| Orbital Eccentricity (e) | 0.16300 |
| Orbital Inclination (i) | 95.0000° |
| Mean Bulk Density | 0.85 g/cm³ (24.3 km/s vesc) |
| Insolation Flux | 69.1705 S⊕ (~94,141 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 52.200 LY (16.007 pc) |