Stardust: We are Dead Stars
By Yash Tomar
Cosmofluencer (Season 04)
Yes, we are made of star stuff, to understand this let’s start from the beginning, right after the Big Bang when the early stars began to form from the newly created Hydrogen(H) and Helium(He) present in the Primordial soup. Then, in the core of the stars, a process called Stellar nucleosynthesis took place.
What is Stellar Nucleosynthesis? (Creation)
When you look up to stargaze at night, you see a tiny, bright, shiny object. But within, this tiny object is a core that is unimaginably hot and dense. There at the core, it is so hot and dense that the Hydrogen(H) atoms overcome the nuclear forces and fuse together.
In this reaction of nuclear-fusion, heat and energy is released, and it is converted into Helium(He) atoms forming a pool of Hydrogen(H) and Helium(He) atoms. This causes the star to collapse into itself and thus begins the next stage of Stellar nucleosynthesis.
As the temperature increases up to a million degrees, Helium(He) starts to fuse into more heavy atoms. Carbon(C) and Oxygen(O), the building blocks of life, are formed. After this stage, most stars die as there is not much energy from the fusion reaction to start the next stage.
Stars like Betelgeuse, a red supergiant in the Orion constellation, use the thermal pressure from nucleosynthesis to counterbalance gravity. As the star collapses after exhausting its fuel, the intense conditions give rise to the formation of heavier elements such as Magnesium (Mg), Neon (Ne), Sodium (Na), and Aluminium (Al). This process produces heavier atoms in the larger and more intense cores of supermassive stars.
How Elements Spread across the Universe (Release)
In a star’s even longer lifetime and towards the last stages of nucleosynthesis, the core is filled with pure Iron(Fe). These elements form a layer-like structure with lighter elements like Hydrogen(H) and Helium(He) on the top and Iron(Fe) in the centre. When no more fuel is left, i.e., nuclear fusion energy is absent, the entire star collapses onto itself, thereby releasing the elements into the lifeless voids of the Universe.
How Scattered Elements Formed Us? (Now)
All the elements are floating in space for a while, and then gravity plays its card in assembling them into a spinning cloud of elements and dust. As this cloud slows down, it forms a hot and dense centre with a spinning disc surrounding the thus formed Planetary Nebula. The dense centre later forms the star like our sun, and the spinning disc becomes planets and other chunks of matter like asteroids and meteors.
As the time passes, one of the planets, like our Earth, had the perfect mix of elements to start life in it from Carbon(C) and Oxygen(O) atoms. Later life evolved into us Humans, and we build everything that we see around us.
Every item in our body was made by a star millions of years ago. The atoms in both of our eyes are formed in a different star. We couldn’t be here if the stars had not formed and exploded, scattering their guts everywhere in the Cosmos; later, to form us. We are Stardust.
References
1. Star Death and the Creation of Elements – Wonders of the Universe: Stardust, preview | BBC
2. We Are Dead Stars | TEDx Talks
3. Neil Degrasse Tyson – We Are Stardust | Evan Pragliola
4. “We Are Star Dust” – Symphony of Science | melodysheep
5. We Are All Made of Stars | Brian Cox and Joe Rogan