HD 69830 c
Astrophysical Synthesis & Habitability Characterization
HD 69830 c is a confirmed sub-neptune exoplanet orbiting the star HD 69830, located approximately 41 light-years (12.56 parsecs) from the Solar System. First announced in 2006 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 3.46 Earth radii (0.31 Jupiter radii) and has a measured mass of 11.8 Earth masses. Combining its mass and radius yields a mean bulk density of 1.57 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.99 g⊕ (9.71 m/s²), and an escape velocity of 20.7 km/s.
In its orbital architecture around HD 69830, HD 69830 c completes one full revolution every 31.56 Earth days at a semi-major axis of 0.186 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 64.1 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.13 carries the world between 0.1618 AU at periapsis and 0.2102 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 567 K (+294°C / +561°F) and receiving 17.42 S⊕ (~23,705 W/m²), HD 69830 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 69830 is classified as an orange K-type star of spectral type K0V with an effective photospheric temperature of 5,385 K, a radius of 0.8869 R☉, a mass of 0.86 M☉, an estimated bolometric luminosity of 0.593 L☉. Stellar evolution modeling indicates an estimated stellar age of 7 Gyr and a metallicity of [Fe/H] = -0.05 dex (near-solar heavy-element abundance). From Earth, HD 69830 shines at apparent V-band magnitude 5.96 (visible to the unaided human eye under dark skies) in the Southern celestial hemisphere. The HD 69830 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 69830 c sharing its stellar neighborhood alongside HD 69830 b, HD 69830 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 69830 |
| Spectral Type | K0V |
| Effective Temp (Teff) | 5,385 K |
| Stellar Radius | 0.8869 R☉ |
| Stellar Mass | 0.8600 M☉ |
| Bolometric Luminosity | 0.593 L☉ |
| Metallicity [Fe/H] | -0.050 dex |
| Stellar Age | 7.000 Gyr |
| Apparent Magnitude | V: 5.960 · G: 5.754 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.186000 AU |
| Orbital Period | 31.56 days |
| Mean Orbital Velocity | 64.1 km/s |
| Orbital Eccentricity (e) | 0.13000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.57 g/cm³ (20.7 km/s vesc) |
| Insolation Flux | 17.4170 S⊕ (~23,705 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 41.000 LY (12.559 pc) |