Gl 49 b

Astrophysical Synthesis & Habitability Characterization

Gl 49 b is a confirmed sub-neptune exoplanet orbiting the star Gl 49, located approximately 32.1 light-years (9.85 parsecs) from the Solar System. First announced in 2019 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.24 Earth radii and has a measured mass of 5.63 Earth masses. Combining its mass and radius yields a mean bulk density of 2.76 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.7 km/s.

In its orbital architecture around Gl 49, Gl 49 b completes one full revolution every 13.851 Earth days at a semi-major axis of 0.0905 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 71.1 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.363, swinging from 0.0576 AU at periapsis out to 0.1234 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 436 K (+163°C / +325°F) and receiving 6.03 S⊕ (~8,206 W/m²), Gl 49 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Gl 49 is classified as a low-mass red dwarf of spectral type M1.5 V with an effective photospheric temperature of 3,805 K, a radius of 0.511 R☉, a mass of 0.515 M☉, an estimated bolometric luminosity of 0.049 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.13 dex (metal-rich relative to the Sun). From Earth, Gl 49 shines at apparent V-band magnitude 9.56 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere.

Discovery Facility: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).