Dying Star

When a stars core stops fusing hydrogen to make helium,it exits the main sequence and enters its death throes.The equilibrium the star fought so arduosly to attatin at the beginning of its life is upset,as the radiation output ceases and the star begins contracting under gravity.The energy generated by this collapse heats up the stellar atmosphere where hydrogen is still present.The stellar atmosphere becomes so hot and pressurized thet fusion of this hydrogen store takes place.This process causes to swell in size to become a giant.

Light echoes

Twenty thousand light years away-at the very edge of our galaxy-starV838 Monocerotis underwent a sudden outburst in January 2002.It became 600000 times brighter than the sun,making it the most iuminous star in the Milky Way.These three images from the Hubble Space telescope chronical the progress of the flare-up,which researches still cannot explain.