Astronomers have observed the core of a dying star, confirming theories about how atoms are formed. This was reported by UNN with reference to phys.org.
Details
According to a publication in the journal Nature, stars are powered by nuclear fusion – a process in which lighter atoms merge into heavier ones, releasing energy.
Fusion occurs in stages throughout a star's life. In a series of cycles, hydrogen (the lightest element) first fuses into helium, and then heavier elements such as carbon are formed. The most massive stars continue fusion up to neon, oxygen, silicon, and finally, iron.
Each burning cycle occurs faster than the previous one. The hydrogen cycle can last millions of years, while the silicon cycle ends in a matter of days.
As the core of a massive star continues to burn, the gas outside the core takes on a layered structure, where successive layers capture the composition of the burning cycle progression.
While all this is happening in the star's core, it also emits gas from its surface, which is carried into space by the stellar wind. Each thermonuclear fusion cycle creates an expanding shell of gas containing a different mixture of elements.
Then, great pressure and temperature cause iron to fuse, but unlike the fusion of lighter elements, this process absorbs energy rather than releasing it.
The release of energy from fusion is what keeps the star from gravity, so the iron core collapses. Depending on how large it was initially, the collapsed core will turn into a neutron star or a black hole.
The collapse process creates a "rebound" that pushes energy and matter outward. This is called a core-collapse supernova explosion.
The explosion illuminates the gas layers that previously separated from the star, allowing us to see what they are made of. In all known supernovae to date, this material was either hydrogen, helium, or a layer of carbon formed in the first two cycles of nuclear burning.
The inner layers (neon, oxygen, and silicon) form only a few hundred years before the star explodes, meaning they do not have time to move away from the star.
Recall
Residents of central Victoria, Australia, reported seeing a large meteor on Sunday that flew across the night sky. Some people described an extremely bright fireball and a loud sound as the object flew overhead.