HD 180053 b
Astrophysical Synthesis & Habitability Characterization
HD 180053 b is a confirmed gas giant exoplanet orbiting the star HD 180053, located approximately 447 light-years (137.04 parsecs) from the Solar System. First announced in 2018 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 13.3 Earth radii (1.19 Jupiter radii) and has a measured mass of 697.319 Earth masses (2.19 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.63 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.94 g⊕ (38.64 m/s²), and an escape velocity of 81 km/s.
In its orbital architecture around HD 180053, HD 180053 b completes one full revolution every 213.72 Earth days at a semi-major axis of 0.843 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 42.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.081 carries the world between 0.7747 AU at periapsis and 0.9113 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 543 K (+270°C / +518°F) and receiving 17.67 S⊕ (~24,053 W/m²), HD 180053 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 180053 is classified as an orange K-type star of spectral type K0 with an effective photospheric temperature of 5,131 K, a radius of 4.06 R☉, a mass of 1.75 M☉, an estimated bolometric luminosity of 10.251 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.25 dex (metal-rich relative to the Sun). From Earth, HD 180053 shines at apparent V-band magnitude 7.93 (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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 180053 |
| Spectral Type | K0 |
| Effective Temp (Teff) | 5,131 K |
| Stellar Radius | 4.0600 R☉ |
| Stellar Mass | 1.7500 M☉ |
| Bolometric Luminosity | 10.251 L☉ |
| Metallicity [Fe/H] | 0.250 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 7.930 · G: 7.703 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.843000 AU |
| Orbital Period | 213.72 days |
| Mean Orbital Velocity | 42.9 km/s |
| Orbital Eccentricity (e) | 0.08100 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.63 g/cm³ (81 km/s vesc) |
| Insolation Flux | 17.6730 S⊕ (~24,053 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 447.000 LY (137.043 pc) |