Arrange the events in the life of a star in the correct order.

all that remains of the star now is the core. in some cases, the star turns into a black hole.

as the nuclear fusion sets off a chain reaction, the nebula gets hotter and brighter and turns into a star.

the star stays in the main sequence stage for a long time.

the star runs out of hydrogen and turns into a planetary nebula or a supernova, depending on its mass.

heavy elements are created when the supernova explodes.

the temperature increases in the center of a nebula, and nuclei begin to fuse.