This guide was impossible To Create Without These Cool Guys and stuff:
(1) Improved Orion Nebula Model ( Link is not Available during the creation period of the guide ) :(


(2) Realistic Nebula Models More Random Nebulas Models Created by Leyo

Thanks a lot to all these Guys.

Some other Guides That can have a Relation to this guide :

https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3306139352
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3328386561
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3081840420

Stars form in Nebulous molecular Clouds through gravity and Nuclear Fusion.
They Take Millions of Years in this process.

As we said, They Build from a dense Molecular region of a nebula. It has a very low-density Area Where Star births. If you create an Earth-sized nebula, it'll weigh only a few Kilograms.
They are less dense than any Vacuum created on Earth.

We are going to take a Nebula and a Hypothetical Star as well as its planets, all will be created in the same Nebula. We will Explain Its main phases during its infancy and before Birth. There will be some Chapters that will Define Changes over hundreds of thousands of years.

Let's Say our Star Can be Born in about 10 Million Years.

First of all Let's See Where Our Star will birth, Look at this Image, Its Orion Nebula and this is Closest Star Forming Region, This nebula Contains approx 180 Star Forming Regions, For instance We take One of them.




In this image You see I have placed mark around some places These are the Regions Where stars forms But You Won't Be able to look those stars until their Shine Reaches to Enough Magnitude That's Why You can't see any star Being Form in such areas. Actually They are Either still Collecting Particles or just started to attract Each other. For Better Understanding You can Check in SpaceEngine and go inside of a nebula and you will see nothing. Obsivously You can't See Sub-atomic Particles on your vision.

We are inside a nebula and we're gonna see a star which is about to be born, rather than a star, you will see Fog interstellar Dust, and Gas.


Let's look at our Area on the Subatomic level. We see the Gas Particles are Constantly Moving in every direction without any obstacles. They are Free to go wherever want; nobody will stop them. Some are colliding with each other and changing their Trajectory.




You see them for several Hundreds of Years and nothing happens, they are just flying and colliding with each other .There is nothing like attraction or gravity. They will probably stay forever in this phase .Our star will never be born. If they are Constantly Going To and Fro,thatt is our main Problem.

If you have a Curious Mind Probably thinking There is Billions to Trillions of Nebulae in universe, If you asked to me that If a nebula can make Hundreds of stars then Why The Nebulae still present in space Because They are Very old maybe Older than Stars, Just Think Not Every Nebulae has Stellar nursery, Some of them are Stellar Remnant, Many are Planetary Nebulae which form when a Red Giant Star Loses its Outer Shell and So on. That's Why Every nebula Ddoesn'tCreate Stars, andevenn when they are creating,wee can't see their Particle interactions Unless We have Proper Equipment. So don't say Star will form from any Nebula. They have a Special Condition For this.

If you wanna know what can be the Reason For the Birth of a star, Just Keep Reading This guide.

As we know, inside a gas, Subatomic particles don't attract by themselves, But They Need a Trigger to get closer to them. So even though they are constantly wandering inside a Gaseous Medium, Colliding Too, they won't attract automatically. When The Flash or Shockwave of Supernovae or Jets of black hole Go Through This Medium, The Photons of Radiation Ionise these particles, and they change their behaviour. When a Shockwave of a supernova travels inside a nebula or such a star-forming region, The Gas clouds get compressed Because Their Movement Field becomes shorterand they are forced to move into a more dense area than before.

Here are some Triggers for Star Formation :

(1) Supermassive Black Holes

(2) Supernovae

(3) Still Unknown

By helping Those Agents, Nebula's Gaseous clouds compress, and the Particles Come close to each other. When they come close enough, they join and become hotter, energetic, massive, and charged. Their mutual gravity Increases as well.

Suppose! Our Star Forming Region has experienced a Supernova Shockwave, and it Became Compressed Like We Changed The Size of a Swimming pool or a Gas Container. As their Free Roaming Place Gets Shorter, They Feel More Pull Toward each other.



In this image, our star-forming area's Particles are in a compressed region, and they are feeling much more pull.




Afterthatt they come close to each other, and when they merge, Their Energy will combine, as a result, they will Attract More particles.



At a certain point, they have gained mass, Heat, and pressure enough to stick their Nuclei with others. Finally, First, But Very Tiny (in Infrared) Glow Comes From There and they continue this process. After some thousands of years, They Will become much larger.

2 million years ago, a supernova's Shockwave Disturbed our forming zone, and it became a large fog-like structure.





Our Fog is still gathering Gases and Particle's Energy is strong enough to generate a Very Dim Light.



In this image, you can see our gas Mist. Let them gather more Gases, temperature, and pressure.

In almost 5 million years, Our Gas cloud has completely changed its appearance. It can glow by its Light, But If you look at our Region, you'll say it's still part of a nebula.




This is the early Stage of our Protostar. This is still Gathering Gas and dust.

We are watching Our Star past 9 Million Years, but Now We see a brighter light coming from our star-forming region. Our star is about to enter its Protostar phase.



A View from the Far Side

After 10 million years, Our Little Star is Ready to govern her System, but still she is forming and has to Make Herself Complete. Our Star Forming Region has completely changed during This Process.
Now, This Zone will be called a Proplyd (ionized Proto-planetary Disk) . Our Star has Almost Gained Enough mass and Features like a Main Sequence Star, But Still She is not completed. Our Star Forming Region still has some Gas and dust, which has not been used as Food for our Baby Star.
So the Rest of the material Will Orbit our Baby Star or Protostar Due to its immense Gravity.




If you look at our Forming Region from the far side, it'll look like a Dark know, torus, Diamond, or just a point.



There she is, inside the shell of Dense Cloud, our baby star is still gathering Gas and Dust. It is ejecting high-velocity jets from its poles.

Our Protostar has some New Structures. Let's know about them.


Protostar

It is our baby star that has been born after a Long long-lasting process of Collapsing Cloud due to the Gravity of its particles. Her core's Temperature is less than 10 million K So when she crosses this temperature, she will start to fuse Hydrogen. She has to get Enough Doses to be Luminous. In this process, it will take about 1 Million Years. The Light coming from her is just by Collapsing Gas and Dust, not by Fusion. Also, she is Larger Than a Star, but course of time, she will become Smaller when she enters in Main sequence Phase. She is still like a Hot and Bright Dense Cloud Rather than a Star.

This is an Important point of our Star. If The Protostar were so massive and Strong with Gravity, Than the current time, Everything Would happen quickly. This means a More Massive star has a shorter life span. Normal Stars form around 10 million years, Massive Stars take only a million years, Small Stars take Hundreds of Millions of Years. Our Sun, like stars, takes 50 million years. When our Star will cross Temperature of 1 Million Kelvin it will start to fuse deuterium or Heavy hydrogen, If The Protostar is not Massive Than 0.08 Ms and Never Reaches Temperature 10 Million Kelvin thus it won't be able to Fuse Normal Hydrogen. It will be called a failed Star or Brown Dwarf


Disk

As The Cloud collapses, itstartst trotatete, and course of time, it gets flat.
Even though our star Has Strong Gravity But she still can't swallow all the Gas and Dust Because Stars have a limit of About 200 Ms (solar Masses). This means if a Protostar reaches 200 Ms, Then It will generate very strong Power, and its gravity can't sustain its internal Pressure, and it will Blow Like a little Nova, and the Star will die. [/b] That's Why They Can't Become Much larger, and the Surrounding gas spins around it. The particles in the disk are constantly moving.


Jets


When Collapsing Cloud Rotates, it forms a strong magnetic field and the Magnetic Field Also Generates Stellar Wind, Which Flows in Outer Space. Normally,there are two jets that come from the rotation Axis of the protostar. When our Star gets enough mass and pressure, Eventually These Jets and Strong Winds will blow out the Shell of this gas and dust. By helping Jets and Winds, our baby star breaks the portion of the nebula, and she will start to float in the interstellar Medium.

Just like hatching a Chick From an egg or the Ejection of a Baby from its mother's Womb :)

Our Baby Star is almost Complete, and the Surrounding Gas and dust will also collapse by its self-gravity. This is called Planetesimal, which Means They are the building Blocks of planets and moons.
If there is enough material, a gas giant or then rocky planet will form because Usually Gas giants have much more gravity than Rocky planets. For many millions of years, these particles will constantly move, collide, and conjugate, and Again Crash into other Particles. Course of time, they will get the size of a Little Piece of rock.




In this Image, we have our star and Its Proto-Planets. They will still collide with each other, and after a Very Long time, They Will gain the size of Earth and the moon. Maybe Jupiter-like Giants form in Cold Regions,so that They Still Suck the Gas and don't create any pieces of stone, meaning they should remain in a Gas state.

After 50 million More Millions of years, Our Star Looks like this image. It was glowing in White and orange colors, but I took its screenshot more artistically. it is an F type Star

So here I have Explained All of the processes that are involved in stellar formation.

As We Mentioned in Section - Triggers for Stellar Formations, it was written that Stars can Form Automatically. Well, this is not true generally.

But We still Don't know How The First Stars were born, Was They Form without Any trigger Because In Early Universe There was not much objects like Nowadays, Supernova Can Start the Stellar formation when its Shockwave and Radiation Arrives and Crosses inside Molecular Clouds but It is supposed There was not enough time For Birth of a star and Death. Maybe The First Black Holes helped the Evolution of those stars, or maybe the Dark Matter.

Perhaps dark Matter Created The First Stars and Galaxies together, just as Binary or multiple-star systems form in a cluster. However, there is ongoing Research on the First stars formed despite No Supernovae or any trigger like that. Black holes also existed in the early ages of the universe. There are a lot of questions, and there must be an answer.


Anyway, Thanks for Reaching This guide and Reading. I wanna say thanks again, whoever made those Beautiful models of Nebulae?

I hope you enjoyed the Guide.

Have a Nice day

Thank you very much :))