Galaxy NGC 4603A has been remarked upon for its easy to spot cepheid pulsating stars.
Gravity tugs the star's atmosphere into the star.
Meanwhile, the pressure of hot gases from the star's interior pushes outward. But no Cepheid star pulsates forever. Some build up into such massive stars that they self-destruct into supernova. Others splinter into a millions of pieces. The bulk of its remains collapses into itself.