Bobbie Jean Carter, the sister of pop stars Nick and Aaron Carter, died Saturday morning in Florida, although her cause of death is currently unknown. “I am in shock from learning of the sudden death of my daughter, Bobbie Jean; and I will need time to process the terrible reality of this happening for the third time,” her mother, Jane Carter, told TMZ. “When I am able to think clearly, I’ll release a fuller statement; but until then I would request to be left to grieve in private.” Bobbie Jean’s death comes a little over a year after her younger brother Aaron, a former child star, was found d…