Ever wondered how star forms? Well, here’s how.

The celestial journey. 1 solar mass, M☉, is the mass of our sun, 2x10³⁰ kg.

A star is born

In our early universe (380,000 years after the Big Bang), the universe was filled with random particles. One can imagine those particles floating through physical space like in Figure (a) below. What we must keep track of is the hyperspace that is created by gravity as it bends spacetime, Figure (b) below. The ellipses simply represent that this happens in all directions.

(a) Physical space of atoms, and (b) hyperspace of atoms.
Atoms forming together in (a) physical space, and (b) hyperspace.
Shout out Wiki for the dope pic — open source the future.
Resistance force counteracting gravity.
A protostar forming in (a) physical space, and (b) hyperspace.

Main Sequence Activated — Small Stars

What happens during main sequence and beyond really depends on the size of the star, so we start with small stars. This includes anything less than ~8 solar masses when they are alive, and <1.4 solar masses at death. One solar mass, M☉, is the mass of our sun, 2x10³⁰ kg. It is evident that stars lose mass as they age, because they release energy; and E=mc² (i.e. if you lose energy in the form of light, then you’re also losing mass).

A star entering main sequence. Blue is helium. Black is hydrogen.
The layers of a star.
Electron degeneracy pressure keeping the star afloat against the collapse of gravity.
Shoutout NASA. Shoutout Hubble. Amazing.
The celestial cycle of small stars on the left.

Main Sequence Activated — Massive Stars

Massive stars start out as stars bigger than 8 Solar Masses while alive, as indicated by the above graphic. They follow a very similar pattern compared to smaller stars with the 3 main differences being: (a) the process lasts millions of years as opposed to billions of years, (b) a star’s core contains a more diverse set of atoms, and (c) the star is much, much bigger.

(a) Hyperspace of a small star. (b) Hyperspace of a massive, more diverse, star.
The Tycho Supernova — shout out NASA. Again, really awesome stuff.
A black hole in hyperspace.


Overall, the formation of stars is a very interesting one. It starts from simple hydrogen atoms (around 10^(-13) cm in size, weighing ~1.7x10^(–27) kg) combining together to form larger and larger objects, like massive stars which can weigh up to 200 solar masses (i.e. 4x10³² kg)! As with everything in life, gravity seems to be the driving force for their creation, life, and ultimate death. We sum up this chapter with a couple graphics to really seal everything in. Again, words only do so much, which is why I littered this article with pictures. The first figure shows the complete lifecycle of stars — yet again.

You’ve seen this before — here it is again.
A scaled out version of the universe.

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