astronomers working at telescopes in the Canary Islands and Spain has detected at least 18 huge gas spheres estimated to have 5 to 15 times the mass of Jupiter

astronomers working at telescopes in the Canary Islands and Spain has detected at least 18 huge gas spheres that are at an estimated 5 to 15 times Jupiter's mass

astronomers is working at telescopes in the Canary Islands and Spain, having detected at least 18 huge gas spheres that are estimated at 5 to 15 times the mass of Jupiter

astronomers, working at telescopes in the Canary Islands and Spain, and has detected at least 18 huge gas spheres estimated at 5 to 15 times the mass of Jupiter

astronomers, working at telescopes in the Canary Islands and Spain, has detected at least 18 huge gas spheres they have estimated as being 5 to 15 times Jupiter's mass