There are 2 basic ways to do this block.
One is to do it like in your picture and do Y-seams.
The other is to divide the center of each star's top and bottom into 2 pieces and then strip sew. Therefore you would sew one lying on its side triangle to 1/2+ of an triangle on end to then another triangle on its side ... and continue. Will try to put a picture of it when I get my scanner up again.