What do those stars mean after subject lines in the archives?

What do those stars mean after subject lines in the archives?

It seems to be connected to relevancy.
When you enter a search term, the software driving this site will rank the results of the search with stars--the higher the number of stars the more relevant the search result is to your query.
This is usually how search algorithms work but the final answer will probably come from the owner of this site.

Yes, that's exactly it.