GJ 896 A b

Astrophysical Synthesis & Habitability Characterization

GJ 896 A b is a confirmed gas giant exoplanet orbiting the star GJ 896 A, located approximately 20.4 light-years (6.26 parsecs) from the Solar System. First announced in 2022 by Very Long Baseline Array using the Astrometry detection technique, this world measures 13.3 Earth radii (1.19 Jupiter radii) and has a measured mass of 718.292 Earth masses (2.26 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.68 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.06 g⊕ (39.81 m/s²), and an escape velocity of 82.2 km/s.

In its orbital architecture around GJ 896 A, GJ 896 A b completes one full revolution every 284.39 Earth days at a semi-major axis of 0.63965 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 24.5 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.35, swinging from 0.4158 AU at periapsis out to 0.8635 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.

❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 127 K (-146°C / -231°F) and an incident flux of 0.04 S⊕ (~58 W/m²), surface water and volatile species on GJ 896 A b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.

The host star GJ 896 A is classified as a low-mass red dwarf of spectral type M3.5 V with an effective photospheric temperature of 3,345 K, a radius of 0.3947 R☉, a mass of 0.436 M☉, an estimated bolometric luminosity of 0.017 L☉. From Earth, GJ 896 A shines at apparent V-band magnitude 10.05 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

Discovery Facility: Very Long Baseline Array · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).