Variable stars exhibit brightness variations due to their unstable nature, particularly in larger stars. These stars can undergo outbursts, creating nebulae while still remaining as stars rather than collapsing into black holes or neutron stars. The variability is attributed to different mechanisms depending on the type of variable star, such as Cepheids. Understanding the Main Sequence is crucial, as most stars experience variability during their lifecycle, especially when transitioning to the giant stage.
PREREQUISITESAstronomy enthusiasts, astrophysicists, and students studying stellar evolution and the lifecycle of stars will benefit from this discussion.
The trouble with an answer is that there are very many different types of variavle stars, and each usually has a different mechanism going on which causes the variability. One type is Cepheids, which you can read about in the thread below.varsha said:i don't get it. really large stars are unstable and there are frequent outbursts. so they are called variable stars. but when they burst they create a nebula and remain as a star right? how is that? shouldn't they turn into a black hole or a nutron star or just a nebula?
or do they just vary in brightness?