HIP 79431 b
Astrophysical Synthesis & Habitability Characterization
HIP 79431 b is a confirmed gas giant exoplanet orbiting the star HIP 79431, located approximately 47.4 light-years (14.53 parsecs) from the Solar System. First announced in 2009 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 13.4 Earth radii (1.2 Jupiter radii) and has a measured mass of 667.415 Earth masses (2.1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.53 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.72 g⊕ (36.48 m/s²), and an escape velocity of 78.9 km/s.
In its orbital architecture around HIP 79431, HIP 79431 b completes one full revolution every 111.7 Earth days at a semi-major axis of 0.36 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 35.1 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.29, swinging from 0.2556 AU at periapsis out to 0.4644 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 177 K (-96°C / -141°F) and an incident flux of 0.22 S⊕ (~297 W/m²), surface water and volatile species on HIP 79431 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HIP 79431 is classified as a low-mass red dwarf of spectral type M3 V with an effective photospheric temperature of 3,191 K, a radius of 0.4786 R☉, a mass of 0.49 M☉, an estimated bolometric luminosity of 0.021 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.4 dex (metal-rich relative to the Sun). From Earth, HIP 79431 shines at apparent V-band magnitude 11.394 (faint and requiring research-grade or CCD telescopic photometry) 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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HIP 79431 |
| Spectral Type | M3 V |
| Effective Temp (Teff) | 3,191 K |
| Stellar Radius | 0.4786 R☉ |
| Stellar Mass | 0.4900 M☉ |
| Bolometric Luminosity | 0.021 L☉ |
| Metallicity [Fe/H] | 0.400 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 11.394 · G: 10.235 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.360000 AU |
| Orbital Period | 111.7 days |
| Mean Orbital Velocity | 35.1 km/s |
| Orbital Eccentricity (e) | 0.29000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.53 g/cm³ (78.9 km/s vesc) |
| Insolation Flux | 0.2179 S⊕ (~297 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 47.400 LY (14.532 pc) |