You might be thinking of aster, not "asters". An aster is a structure formed during mitosis (cell division) in animal cells. It's not a specific part of the cell like a nucleus or mitochondria, but rather a temporary arrangement of microtubules.

Here's a breakdown:

* Microtubules: These are long, hollow tubes made of protein that are part of the cytoskeleton. They provide structure and help with movement within the cell.

* Aster: During mitosis, microtubules emanate from the centrioles (small, cylindrical structures near the nucleus). These microtubules form a star-shaped array called the aster.

* Role of the Aster: The aster helps to pull the chromosomes apart during mitosis by attaching to them and guiding them towards opposite poles of the cell.

So, to answer your question directly, asters are not a part of the cell in the same way that other organelles are. They are a temporary structure formed during mitosis, made up of microtubules.