HD 31253 b
Astrophysical Synthesis & Habitability Characterization
HD 31253 b is a confirmed gas giant exoplanet orbiting the star HD 31253, located approximately 189.6 light-years (58.14 parsecs) from the Solar System. First announced in 2010 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 14.1 Earth radii (1.26 Jupiter radii) and has a measured mass of 197.055 Earth masses (0.62 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.39 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.99 g⊕ (9.71 m/s²), and an escape velocity of 41.8 km/s.
In its orbital architecture around HD 31253, HD 31253 b completes one full revolution every 466 Earth days (1.28Julian years) at a semi-major axis of 1.26 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 29.4 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.3, swinging from 0.882 AU at periapsis out to 1.638 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 14.100 R⊕, HD 31253 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 31253 is classified as a warm F-type star of spectral type F8 with an effective photospheric temperature of 6,130 K, a radius of 1.75 R☉, a mass of 1.7 M☉, an estimated bolometric luminosity of 3.88 L☉. Stellar evolution modeling indicates an estimated stellar age of 3 Gyr and a metallicity of [Fe/H] = 0.17 dex (metal-rich relative to the Sun). From Earth, HD 31253 shines at apparent V-band magnitude 7.133 (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 31253 |
| Spectral Type | F8 |
| Effective Temp (Teff) | 6,130 K |
| Stellar Radius | 1.7500 R☉ |
| Stellar Mass | 1.7000 M☉ |
| Bolometric Luminosity | 3.88 L☉ |
| Metallicity [Fe/H] | 0.170 dex |
| Stellar Age | 3.000 Gyr |
| Apparent Magnitude | V: 7.133 · G: 6.985 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.260000 AU |
| Orbital Period | 466 days |
| Mean Orbital Velocity | 29.4 km/s |
| Orbital Eccentricity (e) | 0.30000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.39 g/cm³ (41.8 km/s vesc) |
| Insolation Flux | 2.0698 S⊕ (~2,817 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 189.600 LY (58.144 pc) |