HD 176986 c
Astrophysical Synthesis & Habitability Characterization
HD 176986 c is a confirmed gas giant exoplanet orbiting the star HD 176986, located approximately 90.6 light-years (27.78 parsecs) from the Solar System. First announced in 2017 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world has a minimum or true mass of 2097.985 Earth masses (6.6 M♃), while its physical transit radius has not yet been geometrically observed.
In its orbital architecture around HD 176986, HD 176986 c completes one full revolution every 16.812 Earth days at a semi-major axis of 0.11873 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 76.8 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.111 carries the world between 0.1056 AU at periapsis and 0.1319 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 558 K (+285°C / +545°F) and receiving 22.90 S⊕ (~31,167 W/m²), HD 176986 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 176986 is classified as an orange K-type star of spectral type K2.5 V with an effective photospheric temperature of 4,931 K, a radius of 0.782 R☉, a mass of 0.789 M☉, an estimated bolometric luminosity of 0.324 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.3 Gyr and a metallicity of [Fe/H] = 0.03 dex (near-solar heavy-element abundance). From Earth, HD 176986 shines at apparent V-band magnitude 8.42 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 176986 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 176986 c sharing its stellar neighborhood alongside HD 176986 b, HD 176986 d.
Discovery Facility: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 176986 |
| Spectral Type | K2.5 V |
| Effective Temp (Teff) | 4,931 K |
| Stellar Radius | 0.7820 R☉ |
| Stellar Mass | 0.7890 M☉ |
| Bolometric Luminosity | 0.324 L☉ |
| Metallicity [Fe/H] | 0.030 dex |
| Stellar Age | 4.300 Gyr |
| Apparent Magnitude | V: 8.420 · G: 8.142 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.118730 AU |
| Orbital Period | 16.812 days |
| Mean Orbital Velocity | 76.8 km/s |
| Orbital Eccentricity (e) | 0.11100 |
| Orbital Inclination (i) | 0.2419° |
| Insolation Flux | 22.9000 S⊕ (~31,167 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 90.600 LY (27.784 pc) |