The Rigid Rocky Horizon of Tidally Locked Exoplanet GJ 273b
Located just over 12 light-years from our solar system, GJ 273b represents a primary case study in the mechanics of tidally locked worlds . Orbiting the red dwarf star Luyten's Star , this super-Earth occupies a stable orbital path that has, over geologic epochs, synchronized its rotation with its revolution. The result is a planetary body permanently partitioned into two distinct thermal hemispheres: an eternal day-side bathed in the steady, crimson-hued flux of its host star, and an perpetual night-side trapped in the darkness of a frozen vacuum. Geologically, GJ 273b is characterized by a high-density composition, likely dominated by silicate rock and a significant iron-nickel core. Without the mitigating influence of a rapid diurnal cycle, the atmospheric dynamics of the body are driven almost entirely by thermal gradients between the substellar point —where the star is fixed at the zenith—and the antistellar point . The primary atmospheric constituents are...