Supernovae

Basics

A supernova is the explosive event marking the end of a star’s life cycle.
These explosions are amongst the most powerful events in the universe, releasing immense amounts of energy.
Supernovae are rare phenomena - on average, a galaxy like the Milky Way experiences one to two supernovae per century.

There are two main types of supernovae: Type I and Type II.
Type I supernovae lack hydrogen lines in their spectrum and are suspected to occur in binary star systems when a white dwarf star accretes matter from its companion until it reaches a critical mass.
Type II supernovae demonstrate prominent hydrogen lines in their spectrum and take place at the end of a massive star’s life when nuclear fusion ceases in its core due to lack of fuel, leading to gravitational collapse.

The explosion of a supernova can outshine an entire galaxy for a short period of time.
Supernovae scatter enriched material into space, contributing to the dispersion of elements needed for the formation of new stars, planets, and, potentially, life.
The core of the star left after a Type II supernova can become a neutron star or, if massive enough, a black hole.
Supernovae can also release high energy radiation and particles, influencing the dynamics of interstellar medium and potentially triggering the formation of new stars.
Observing supernovae in other galaxies gives vital clues about their distance from us, aiding our understanding of the universe’s expansion.
The energy from a nearby supernova could potentially affect life on Earth, although such events are rare.

The remnants of a supernova explosion can emit light for hundreds or thousands of years, forming a supernova remnant.
These remnants can be observed in all wavelengths of the electromagnetic spectrum.
Among the most famous supernova remnants is the Crab Nebula, located in the constellation of Taurus.