HD 164595 b
Astrophysical Synthesis & Habitability Characterization
HD 164595 b is a confirmed sub-neptune exoplanet orbiting the star HD 164595, located approximately 92.2 light-years (28.25 parsecs) from the Solar System. First announced in 2015 by Haute-Provence Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 4.16 Earth radii (0.37 Jupiter radii) and has a measured mass of 16.14 Earth masses. Combining its mass and radius yields a mean bulk density of 1.24 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.93 g⊕ (9.12 m/s²), and an escape velocity of 22 km/s.
In its orbital architecture around HD 164595, HD 164595 b completes one full revolution every 40 Earth days at a semi-major axis of 0.23 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 62.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.088 carries the world between 0.2098 AU at periapsis and 0.2502 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 589 K (+316°C / +601°F) and receiving 19.67 S⊕ (~26,770 W/m²), HD 164595 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 164595 is classified as a solar-type yellow star of spectral type G2 V with an effective photospheric temperature of 5,790 K, a radius of 1.0236 R☉, a mass of 0.99 M☉, an estimated bolometric luminosity of 1.056 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.12 Gyr and a metallicity of [Fe/H] = -0.04 dex (near-solar heavy-element abundance). From Earth, HD 164595 shines at apparent V-band magnitude 7.086 (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: Haute-Provence Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 164595 |
| Spectral Type | G2 V |
| Effective Temp (Teff) | 5,790 K |
| Stellar Radius | 1.0236 R☉ |
| Stellar Mass | 0.9900 M☉ |
| Bolometric Luminosity | 1.056 L☉ |
| Metallicity [Fe/H] | -0.040 dex |
| Stellar Age | 7.120 Gyr |
| Apparent Magnitude | V: 7.086 · G: 6.895 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.230000 AU |
| Orbital Period | 40 days |
| Mean Orbital Velocity | 62.6 km/s |
| Orbital Eccentricity (e) | 0.08800 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.24 g/cm³ (22 km/s vesc) |
| Insolation Flux | 19.6697 S⊕ (~26,770 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 92.200 LY (28.254 pc) |