extrinsic variables (examples)

They are stars that pass in front of each other, causing that we can not receive al the light from that star making it seem that it is less brighter because its brightness is substracted but it is not and when they rotate with each other but not passing in front the brightness is higher because they add up so it all depends of a system of two stars

are variable stars that show small light changes caused by patches of light spots on their surfaces. They may have bright spots at the magnetic poles, making it depend on a system of two stars