In the bedknobs and broomsticks it is called "Star of Astoroth" and is as pictured int he attachement.
The "seal of astaroth" (different spelling) is the center part of the image in the OP. It is one of the seals of solomon from the grimour the keys of solomon.
What is interesting is the seal is intended to cast real magic,much as is the theme of bedknobs and broomsticks.