Board Thread:Questions and Answers/@comment-68.38.63.82-20140802181548/@comment-107.207.34.172-20141229003212

As far as I can remember about the Guardians of the Galaxy in the comics, Xandar is in the Andromeda Galaxy. The 9 Realms of the Worlds Tree, on the other hand, is in the Milky Way Galaxy. This explains why Xandar is not part of the 9 Realms, therefore not the Asgardians' duty to protect. However, this doesn't mean that the Bifrost is limited to just open wormholes between the 9 Realms.