Gl581 Preprint

This document summarizes the discovery of a fourth planet orbiting the red dwarf star GJ 581. The planet, called GJ 581e, has a minimum mass of 1.9 Earth masses and orbits with a period of 3.15 days, making it the innermost planet in the system. Updated radial velocity measurements also allowed the researchers to correct the orbital period of the outermost planet GJ 581d, determining it to be 66.8 days rather than the previously reported 83 days. This revised period places GJ 581d within the star's habitable zone. The researchers conclude the GJ 581 system has 4 planets, with the detection of GJ 581e being the lowest mass exoplanet