were first detected using the HARPS spectrometer at the European Southern Observatory's La Silla Observatory in Chile. Further observations by two other spectrometers — HIRES at the Keck Observatory in Hawaii and the PFS instrument at Chile's Magellan II Telescope — backed up the finds.

The team didn't expect to find a possibly habitable world around Kapteyn's Star, which is one-third as massive as the sun but so close to Earth that it's visible in amateur telescopes, in the southern constellation of Pictor.

"We were surprised to find planets orbiting Kapteyn's Star," Anglada-Escude said. "Previous data showed some moderate excess of variability, so we were looking for very short-period planets when the new signals showed up loud and clear."

Kapteyn b lies in the star's habitable zone, the range of distancespresence and long-term survival of a planetary system seems a remarkable feat given the peculiar origin and kinematic history of Kapteyn’s star," the researchers write in the new study, which will be published in the Monthly Notices of the Royal Astronomical Society. "The detection of super-Earth mass planets around halo stars provides important insights into planet-formation processes in the early days of the Milky Way."

The new discovery is an exciting one that could inform the search for alien life throughout the galaxy, outside researchers said.

"It suggests that many potentially habitable worlds will be found in the next years around nearby stars by ground-based and space-based observatories such as ESA's PLATO mission," said Richard Nelson of Queen Mary University of London, who was not a part of the study