HD 165155 b
Astrophysical Synthesis & Habitability Characterization
HD 165155 b is a confirmed gas giant exoplanet orbiting the star HD 165155, located approximately 206.6 light-years (63.36 parsecs) from the Solar System. First announced in 2016 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.2 Earth radii (1.18 Jupiter radii) and has a measured mass of 918.529 Earth masses (2.89 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.2 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 5.27 g⊕ (51.68 m/s²), and an escape velocity of 93.3 km/s.
In its orbital architecture around HD 165155, HD 165155 b completes one full revolution every 434.5 Earth days (1.19Julian years) at a semi-major axis of 1.13 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 28.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.2 carries the world between 0.904 AU at periapsis and 1.356 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.200 R⊕, HD 165155 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star HD 165155 is classified as a solar-type yellow star of spectral type G8 V with an effective photospheric temperature of 5,426 K, a radius of 0.95 R☉, a mass of 1.02 M☉, an estimated bolometric luminosity of 0.702 L☉. Stellar evolution modeling indicates an estimated stellar age of 11 Gyr and a metallicity of [Fe/H] = 0.09 dex (metal-rich relative to the Sun). From Earth, HD 165155 shines at apparent V-band magnitude 9.36 (accessible to binoculars and small amateur telescopes) in the Southern 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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 165155 |
| Spectral Type | G8 V |
| Effective Temp (Teff) | 5,426 K |
| Stellar Radius | 0.9500 R☉ |
| Stellar Mass | 1.0200 M☉ |
| Bolometric Luminosity | 0.702 L☉ |
| Metallicity [Fe/H] | 0.090 dex |
| Stellar Age | 11.000 Gyr |
| Apparent Magnitude | V: 9.360 · G: 9.214 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.130000 AU |
| Orbital Period | 434.5 days |
| Mean Orbital Velocity | 28.3 km/s |
| Orbital Eccentricity (e) | 0.20000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.2 g/cm³ (93.3 km/s vesc) |
| Insolation Flux | 0.5482 S⊕ (~746 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 206.600 LY (63.357 pc) |