Take the tour ×  A star is probably visible/detected by it's
radiation. But that star may or may not belong to our own galaxy
... yet news reports speak of detecting a star/nova in a distant
galaxy.  How does one determine whether the star she/he views
belongs to Milky Way, or some other galaxy ... or is galactic
orphan? Is it merely a matter of the distance to that star?
share|improve this question add comment  3 Answers  up vote 3
down vote accepted  Every ordinary star we are able to
individually observe is a part of the Milky Way. Well, except
for stars in a small number of very nearby galaxies but even
galaxies such as Andromeda look like a "continuum" so we're not
observing the stars individually although we see that the galaxy
isn't just a point.  Only if a star goes nova (a lethal nuclear
explosion of a white dwarf star) of supernova (a similar
explosion but stronger), it may be observed outside the Milky
Way. In all such cases we've experienced, one may always
identify a galaxy at the same location