I recall reading about a triple conjunction of the planets, probably Jupiter, Venus, and I don't recall the third, which coincided with the approximate time of Jesus' birth. Is this what you're hinting at? I don't doubt it, as the calculations have been reportedly done by reputable astronomers. (I don't doubt the existence of Jesus either, just in case you've absorbed some of the rants which appear regularly in these threads. I've been accused of everything, but I generally don't respond to such material.)
A conjunction is the only one known to have happened around then (although timing is unsure given that we don't really know the date of Jesus' birth). But conjunctions are pretty common and non-spectacular, and it's hard to see why it would be called just a "star."