<Li> Gamma Cephei Ab : The radial velocity variations of the star Gamma Cephei were announced in 1989 , consistent with a planet in a 2.5 - year orbit . However , misclassification of the star as a giant combined with an underestimation of the orbit of the Gamma Cephei binary , which implied the planet 's orbit would be unstable , led some astronomers to suspect the variations were merely due to stellar rotation . The existence of the planet was finally confirmed in 2002 . </Li>
<Li> Gamma Cephei Ab : The radial velocity variations of the star Gamma Cephei were announced in 1989 , consistent with a planet in a 2.5 - year orbit . However , misclassification of the star as a giant combined with an underestimation of the orbit of the Gamma Cephei binary , which implied the planet 's orbit would be unstable , led some astronomers to suspect the variations were merely due to stellar rotation . The existence of the planet was finally confirmed in 2002 . </Li>
the first series of extrasolar planets that were discovered were found by which method
the first series of extrasolar planets that were discovered were found by which method
radial velocity variations
radial velocity variations