System: YZ Ceti
Discovered by: European Southern Observatory
Date: August 14, 2017
Key Facts: Three Earth-mass worlds found around a small red star only 12 light-years away.
What's new: YZ Ceti is the nearest multi-planet system found orbiting a red dwarf star or "M dwarf." While the three planets are outside their star's habitable zone, they are all about the same mass as Earth. YZ Ceti b, c, and d are the lowest mass planets found with the planet-hunting method radial velocity. NASA's TESS and James Webb telescopes will study more exoplanets around nearby stars in 2018, in hopes of finding another Earth.
See details and check the official NASA planet count at the NASA Exoplanet Archive
Paper: "A system of Earth-mass planets around the nearby M dwarf YZ Cet"