Supernovae

Many of us have likely seen the visually appealing images of supernovae out there. These colorful, bright explosions that occur within the dark depths of space never fail to elude us. However, what causes them?

When the core of a white dwarf or star with a high mass starts to massively compress, shock waves are produced which break up the atomic nuclei of the body into electrons, protons, and neutrons. As they come back to re-merge into neutrons, they also produce neutrinos(subatomic particles that don't really interact with other forms of matter). While these neutrinos don't interact with other matter technically, their extreme energy outputs cause them to force the outer layers of the star to break apart. This leaves the core(which is now a neutron star), which is now compressed significantly with a far higher density, intact but the outer layers are expelled in an extremely bright explosion known as a supernova. There are two types of supernovae: Type I(Caused by the collapse of a white dwarf above the Chandrasekhar Limit) and Type II(Caused by an extremely massive star collapse).

Now, supernovae themselves are very intriguing when it comes to their effects on the greater universe. Supernovae are the main energy source for cosmic rays, which are high-speed atomic nuclei that can theoretically travel the universe and can affect life on our planet by creating unstable mutations which lead to evolution.

One of the most notable effects of supernovae is that they cause supernova nucleosynthesis which in turn creates greater concentrations of the elements found in stars including other elements. Supernova nucleosynthesis is the process by which nucleons(particles found in atomic nuclei) come together to form full atomic nuclei with the electrons in the surrounding explosion. This creates elements like gold, silver, and uranium, just to name a few. In fact, most of the elements from oxygen(16) to rubidium(37) on the periodic table are formed through supernovae(the ones before oxygen come mainly from stars).

The material formed by supernovae goes into the interstellar medium as hot clouds of gas. This allows for the formation of regions of large molecules, like molecular clouds. This means that supernovae play an instrumental role in the formation of stars and planetary disks. In a way, this makes the process of stellar evolution cyclic because stars die into supernovae which help create more stars.

However, not everything about a supernova is exactly warm and bright. Supernovae emit extreme forms of heat and radiation which would likely be problematic for any life that lives near them. This is of importance because we know of many exoplanets that lie within the habitable zone of their stars. However, if those stars are near other stars which will eventually go supernova(or the stars that the exoplanets orbit themselves will go supernova), then the life that those exoplanets could potentially harbor would be in for a bad time. This implies that being within the habitable zone isn't the only important parameter for the conditions of life on an exoplanet. The relative distance an exoplanetary system is to a supernova is also extremely important.