Final answer:
A Type II supernova occurs when a massive star's core collapses after iron accumulates and surpasses the Chandrasekhar limit. The collapse results in a neutron star and an explosion that disperses heavy elements into space. These events can form pulsars, observable through focused radiation beams.
Step-by-step explanation:
A Type II supernova is a catastrophic stellar event triggered by the collapse of a massive star's core, typically one that has run out of nuclear fuel and cannot support itself against gravitational collapse. During the life cycle of a massive star, after it exhausts hydrogen, the core moves onto fusing helium and gradually heavier elements. This fusion process continues until iron accumulates in the core. Since iron fusion is endothermic, it absorbs energy instead of releasing it, halting the production of nuclear energy and the outward pressure that supports the star against gravity. When the iron core exceeds the Chandrasekhar limit, but is less than 3 Msun, it collapses, reaching densities higher than that of an atomic nucleus and forming a neutron star. This collapse sends out a shock wave that blows the star's outer layers away in a Type II supernova explosion, leading to the production of elements heavier than iron and dispersing chemical elements into space. Such a supernova can also give birth to a rapidly rotating and highly magnetic neutron star, observable as a pulsar, if its focused radiation is pointing toward Earth.