HD 174205 b
Astrophysical Synthesis & Habitability Characterization
HD 174205 b is a confirmed gas giant exoplanet orbiting the star HD 174205, located approximately 763.3 light-years (234.03 parsecs) from the Solar System. First announced in 2022 by Bohyunsan Optical Astronomical Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13 Earth radii (1.16 Jupiter radii) and has a measured mass of 1334.879 Earth masses (4.2 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.35 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 7.9 g⊕ (77.47 m/s²), and an escape velocity of 113.4 km/s.
In its orbital architecture around HD 174205, HD 174205 b completes one full revolution every 582 Earth days (1.59Julian years) at a semi-major axis of 1.7 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 31.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.4, swinging from 1.02 AU at periapsis out to 2.38 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 822 K (+549°C / +1020°F) and receiving 82.70 S⊕ (~112,553 W/m²), HD 174205 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 174205 is classified as an orange K-type star of spectral type K2 with an effective photospheric temperature of 4,308 K, a radius of 26.6 R☉, a mass of 1.8 M☉, an estimated bolometric luminosity of 218.653 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.7 Gyr and a metallicity of [Fe/H] = -0.28 dex (metal-poor relative to the Sun). From Earth, HD 174205 shines at apparent V-band magnitude 6.282 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere.
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: Bohyunsan Optical Astronomical Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 174205 |
| Spectral Type | K2 |
| Effective Temp (Teff) | 4,308 K |
| Stellar Radius | 26.6000 R☉ |
| Stellar Mass | 1.8000 M☉ |
| Bolometric Luminosity | 218.653 L☉ |
| Metallicity [Fe/H] | -0.280 dex |
| Stellar Age | 1.700 Gyr |
| Apparent Magnitude | V: 6.282 · G: 5.898 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.700000 AU |
| Orbital Period | 582 days |
| Mean Orbital Velocity | 31.8 km/s |
| Orbital Eccentricity (e) | 0.40000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 3.35 g/cm³ (113.4 km/s vesc) |
| Insolation Flux | 82.6990 S⊕ (~112,553 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 763.300 LY (234.027 pc) |