How is a star born or formation, How stars die, Define the star and Types of stars . All the information you need to know about the stars, Supernova and Neutron star:-
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| How is a star born, How stars die, Define and Types of stars |
Do you see that star, which lights up in the sky at night!!! It may not be a star but just the light of a star that died thousands of years ago, given the huge distances between the stars far from us, their light may need long light years to reach us, but how do these stars form in this vast universe?, and why do those stars die (or explode) At the end of her life?? And what makes it this way???
Many questions revolve in our minds when contemplating the sky at night, especially when thinking about the largest bodies in the visible universe, the bodies that supply our planet and all living creatures with the energy necessary for the continuation of life.
First: What are the stars?
Stars are bodies with a spherical shape consisting of a combination of hydrogen and helium gases, which produce light and heat as a result of the massive nuclear reactions that occur in the interior of stars.
_ Types of stars:-
Stars can be classified according to several factors, including: star color, density, size, color spectrum, and age of the star.
This is the classification of stars according to their size and color:-
1- Main Sequence Stars
Main sequence stars make up the majority of stars in the universe (about 90% of stars are main sequence stars), including our Sun.
2- White dwarf stars
White dwarfs are the remnants of stars that have used up all their energy, and they are stars with a higher density compared to the Sun and some other stars.
Stars of low and medium mass (less than 8 times the mass of the sun) will eventually turn into white dwarfs, and our sun will also become a white dwarf after all its fuel has been consumed.
3- Brown dwarfs stars
They are celestial bodies that are not massive enough to sustain the nuclear fusion of hydrogen as occurs in ordinary stars, and therefore do not reach the luminosity of stars.
Many scientists call them "failed stars"
4- Red dwarf stars
The most common type of stars in our galaxy is the "Milky Way", and they are stars whose light is so weak that they cannot be seen with the naked eye from Earth.
The life of these stars is very long compared to the age of the sun, as a result of the decrease in the amount of radiation emitted from them, which leads to a prolongation of their life.
5- Red giant stars
They are dying stars (that is, they are in the last stage of their life).
Throughout the life of stars, there is a balance between the internal pressure of hydrogen nuclear fusion and the external pressure of gravity, when the star exhausts most of its energy, this balance is disturbed and the star begins to swell until it reaches a size about 100-1000 times our sun today, and turns into a red giant star.
Our sun will also become a red giant at the end of its life in about 5 billion years
6- Blue giant stars
It is considered one of the hottest and brightest stars.
Its temperature ranges between 10,000 - 50,000 Kelvin.
Its luminosity ranges from 10,000 to a million times that of the sun.
As for the size of the blue giant stars, they are larger than the sun, but smaller than the red giant stars .
7- Neutron stars
They are stars of very small size compared to other stars (the size of a city) with a diameter of about 20 km.
Formed by the explosion of stars that are 4-5 times the mass of the sun, they are so dense stars that a tiny part of them the size of a sugar cube weighs a billion tons.
On average, the gravity on a neutron star is two billion times stronger than Earth's, and is the most gravitational celestial body after black holes.
A neutron star can also rotate at a speed of 43,000 times per minute.
Second: How are stars formed?
Most types of stars are originally composed of other stars such as red giant stars which are the same main sequence stars but at the end of their life, and also neutron stars that arise from the explosion of a huge star.
But how do stars arise from the beginning??
The beginning of the formation of stars arises from the gathering of clouds of gas and dust in space, which is known as the nebula, by the action of gravity the gas molecules gather together, the majority of the gas in the nebulae is hydrogen and helium.
When gas molecules gather in the center of the cloud, its temperature increases due to the pressure caused by gravity.
When the temperature becomes high enough in the core of the gas cloud, the process of nuclear fusion of hydrogen begins, converting hydrogen into helium, forming a protostar.
The energy resulting from this nuclear fusion is what produces starlight, and it is also the energy that makes the star stable and the star's core does not collapse on itself.
Explaining the balance of the star structure in a simplified way:-
In the core of stars, as a result of nuclear reactions, hydrogen atoms are transformed into helium. These nuclear reactions produce energy emanating from the star’s core. This energy causes the star’s core to expand. In contrast to this expansion, the outer layer of the star presses on the star’s core by the force of gravity, and this is what makes the star balanced.
The expansion that results from the core of the star is balanced with the external pressure that results from gravity.
Not all the material in the nebula turns into a star - the remaining dust can turn into planets, asteroids, comets....or it may remain dust as is.
This process takes a very long time for the gas cloud to turn into a luminous star, the formation of a star the size of our sun takes about 50 million years.
The colors of the stars vary from bluish-white and yellow to orange and red, and the difference in the colors of the stars is due to the composition and temperature of the star. The higher-temperature stars tend to be blue, while the medium-low-temperature stars are red like the sun.
The color of the star can also change over time.
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Third: Why, how and when do stars die?
The star remains stable and radiates light and heat as long as the process of nuclear fusion of hydrogen and its conversion to helium continues, but when the star loses all the amount of hydrogen inside and turns all the hydrogen into helium, the star cools from the inside and the energy generated from the star’s core decreases and thus the external gravitational forces overcome the inner layer of the star and make The star collapses on itself, loses its balance and begins to enter the dying stage.
How stars die and how long they live varies according to the star's size and mass.
Huge stars that are several times the size of the sun have a much shorter lifespan than others, because the larger the star, the greater the amount of energy it consumes, and thus this energy runs out quickly and the star dies in a great explosion called: a supernova
_ Stages of death of medium-sized stars (such as the sun):
When stars the size of our sun lose all their nuclear fuel, they begin to shrink due to the prevailing external gravity and the lack of energy from the core of the star
The shrinkage process continues until the star's density becomes very high, at which point the contraction stops and the star begins to inflate, reaching several times its original size and then turning into a giant red star, after which the star begins to lose its mass and the star releases its outer layers into space in the form of huge clouds of gas.
The star loses a large part of its structure, eventually turning into a cold white dwarf star.
These are the same stages that the sun will go through at the end of its life, it will begin to shrink and then swell to more than twice its size, as it will swallow Mercury, Venus, and perhaps the Earth as well, and then cool down to become a white dwarf.
At that time, all living creatures and all aspects of life on planet Earth will be over.
But there is no need to worry now, as the sun is still in its youthful stage and will continue to shine for another 5 billion years.
At that time, humans may have been able to find a home other than the earth.
_ Stages of death of huge stars:-
Stars more than twice the mass and volume of the Sun (4-5 times the mass of the Sun) do not turn into white dwarfs When the energy of these stars runs out, the star begins to collapse on itself and shrink, and its density becomes very high, and it will continue to shrink more and more because the huge pressure resulting from the star's huge mass cannot be stopped by any force.
Then the star's energy explodes in a massive "supernova" explosion that shines more brightly than anything in the cosmos , more than all the stars in the galaxy combined together.
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