Seven Stars and Seven Stones

[Angry Hill Troll]

Tall ships and tall kings Three times three
What brought they from the foundered land Over the flowing sea?
Seven stars and seven stones And one white tree.

I know what the seven stones are (the palantiri), but what about the seven stars?

From doing a search, I find that the standard of Elendil's house consists of seven stars and the White Tree. Also, the chief palantir in Gondor was kept at the Dome of Stars in Osgiliath. One fanfic I've read interprets this as having been a sort of planetarium showing the stars as they appeared from Numenor. Is there any evidence from Tolkien's writings to support this interpretation?

Does "seven stars" simply refer to the design of Elendil's banner, or were there any actual star shaped objects carried from Numenor?