(Phys.org)—Using NASA’s prolonged Kepler mission, known as K2, astronomers have discovered a new Neptune-sized planet in a binary star system in the Hyades open cluster. The newly found exoworld, designated K2-nnnA b, is the first known Neptune-sized planet in a binary system within an open cluster. The finding was reported Sept. 29 in a paper published on the arXiv pre-print server.