Astronomers have detected mysterious radio signals coming from the direction of a small, dim star located about 11 light-years from Earth. The signals came from a red dwarf star - Ross 128 (GJ 447) - which is around 2,800 times dimmer than the Sun and is not yet known to have any planets, researchers said. The "strange" radio signals were detected by astronomers at the University of Puerto Rico in May, using the Arecibo Observatory, which is a massive radio telescope built inside of a Puerto Rican sinkhole. Although unlikely, the possibility that signals came from intelligent extraterrestrial life cannot be ruled out yet, said Abel Mendez, an astrobiologist. "In case you are wondering, the recurrent aliens hypothesis is at the bottom of many other better explanations," Mendez said.