Nomiĝi is intransitive. The root verb nomi means to name (someone) . Nomigi (without the circumflex) can be thought of as nomi (to name) + igi (to cause). So:
Mi nomiĝis Danielo means my name is Daniel
Mi nomis mian filon Danielo means I named my son Daniel.
I am not sure what Mi nomigis iun would mean...
That is even kind of odd in English. In “We call the green stars” the object of the main verb (call) is “the green stars”; that is, “the green stars” are the ones who are being called (by us). Then you're actually using a different meaning of the verb to call: Ni vokas la verdajn stelojn.