Alcor and Mizar, were the first binary stars -- a pair of stars that orbit each other -- ever known. Now, astronomers have made the surprise discovery that Alcor is also actually two stars, and is ...

The first large black holes in the universe likely formed and grew deep inside gigantic, starlike cocoons that smothered their powerful x-ray radiation and prevented surrounding gases from being blown away, says a new study led by the University of Colorado at Boulder.