In the post page, what do the stars under the posts signify?

I've worked out that yellow means a child post and green means a parent, but what do red/black mean?

<<github.com/myimouto/myimo...elpers/PostHelper.php#L94|If either dimension is over 1500px>> then the star is dull red instead of black. Posts flagged for deletion are bright red.

Ah cheers, thought it might be something like that. Been bothering me for a while.