GJ 27.1 b

Astrophysical Synthesis & Habitability Characterization

GJ 27.1 b is a confirmed sub-neptune exoplanet orbiting the star GJ 27.1, located approximately 77 light-years (23.61 parsecs) from the Solar System. First announced in 2014 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 3.66 Earth radii (0.33 Jupiter radii) and has a measured mass of 13 Earth masses. Combining its mass and radius yields a mean bulk density of 1.46 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 21.1 km/s.

In its orbital architecture around GJ 27.1, GJ 27.1 b completes one full revolution every 15.819 Earth days at a semi-major axis of 0.101 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 69.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.08 carries the world between 0.0929 AU at periapsis and 0.1091 AU at apoapsis, driving measurable seasonal insolation cycles.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 387 K (+114°C / +237°F) and receiving 2.55 S⊕ (~3,469 W/m²), GJ 27.1 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star GJ 27.1 is classified as a low-mass red dwarf of spectral type M0.5 V with an effective photospheric temperature of 3,542 K, a radius of 0.5189 R☉, a mass of 0.53 M☉, an estimated bolometric luminosity of 0.038 L☉. From Earth, GJ 27.1 shines at apparent V-band magnitude 11.45 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.

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