Our Universe | The interesting life of the stars

oscarcc89 (71)in #steemstem • 7 years ago

Birth...

Within the large cold clouds of gas and dust small particles begin to pile up.

^{Eagle Nebula - M16. "The Pillars of Creation". Credits: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

Click here to see it in high definition.}

The Pillars of Creation, are a stellar nursery where the process of new stars is developed. Located 7,000 light years from Earth. The pillars are part of the Eagle Nebula (M16) one of the largest regions of star formation in the universe.

The pillars are very high clouds of dust and hydrogen. Hydrogen is the simplest and most abundant element in the universe, it is the fundamental component for the formation of stars.

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Within a nebula over millions of years clusters of this gas and dust merge into smaller clouds joined by a force we all know ...

The gravity

Its own gravitational force and the pressure of nearby stars make these little clusters join in a single great mass. Each contracted cloud can produce from a few tens of stars to thousands of stars. As gravity contracts the cloud, the heat begins to increase.

In a few thousand years the cloud turns into a flat disk. Gravity causes a sphere to form in the center of the disk.

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Like a vacuum cleaner, monstrous, the gravitational force attracts more and more particles of gas and dust. The gravitational force grows so much that the pieces of matter that fall faster and faster at its center begin to warm up. The internal temperature rises to over one million degrees. This brilliant system is called Protostar.

10 million years later, the burning hydrogen nucleus heats up to over 10 million degrees. Subatomic particles called protons, collide with each other at tremendous speeds. The normal electromagnetic force of repulsion between protons gives way to the force of the impact of the particles. The protons fuse, so called thermonuclear fusion, forming helium.

A star has been born!

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This nuclear reaction produces the energy that the star will feed on throughout its life. Providing a constant source of light and heat.

After his birth the life of a star will be a constant struggle, a war without quarter against gravity. The star tries to avoid collapse, since gravity tries to crush it.

The heat causes all the particles of the star to move rapidly outward which produces a pressure, which helps a star resist gravity.

The force exerted towards the outside is equal to the opposite force that gravity does. Keeping the life of the star in balance. Scientists recognize this phase as the main sequence. ^{img source}

Not all the stars in the main sequence are the same, some are smaller than the sun. Others are much larger and hotter.

The light that emits from the stars can tell how hot it is, a star that emits a blue or ultraviolet hue is hotter than one that emits yellow or red light.

The small cold and red stars, like Alpha Centauri C, the closest to the sun. They are known as red dwarfs.

^{Alpha Centauri C. img source}

Its mass can be 10 times smaller than the mass of the sun, and the temperature on its surface thousands of degrees colder. They are the most common stars in the universe.

^{Credits: ESO.org}

There are also the Blue Supergiant, with an average temperature of 25,000 ° C.

They can have a mass 200 times greater than the sun and be 10 thousand times brighter.

The mass is a factor that influences the life of a star. The most massive stars have a shorter life, while the less massive ones have a long life.

It seems strange, does not it?

The more mass a star has, the higher the temperature, the pressure, the speed of fusion, everything accelerates in proportion to the mass, thus depleting its fuel much faster. A massive star can die in a million years.

While the life of the massive stars is measured in millions, the smallest stars are measured in tens of billions, or even billions of years.

Death...

But no star including the sun remains in the main sequence indefinitely. This phase lasts while the star has fuel. When it is exhausted, the merger ceases, and gravity wins.

The size of a star does not affect its longevity, but it determines how it will die. The massive stars disappear in a violent explosion. While the smaller ones are condemned to be consumed slowly.

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Our Sun, a middle-aged star. It has been slowly consuming its reserves of hydrogen. Scientists predict that within 5 billion years the sun will deplete its fuel, at which time its reserves of hydrogen will be completely exhausted. Nuclear fusion will stop and gravity will begin to crush it. Then, the situation will be desperate.

As it contracts, the star receives help from nature. The core overheats thanks to the same gravitational pressure that tries to crush it. Once it reaches 100 million degrees. The sun turns helium into coal in a desperate move for survival.

All this happens during the last 10% of the life of a star. The enormous heat caused by the combustion of Helium causes the outer layers of the star to swell. The atmosphere will begin to evaporate, in a series what they call "cosmic belches", will expel the outer layer of gases that gravity contains. Causing the phenomenon called planetary nebula.

^{The Helix Nebula. Credits: NASA, ESA, y C. R. O'Dell.. Click here to see it in high definition.}

In the center of the planetary nebula our star remains, working more and more for its survival. After converting hydrogen into several increasingly heavy elements to lengthen its life, the last element is iron. The iron core of the star is compressed until it reaches a diameter of 15 km. For a moment the core bounces, hitting the outer layers of the star and causing one of the biggest explosions in our universe.

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Background: July 4, 1054

The surprising appearance of a new star was recorded in China. They were so bright that they could be seen even during the day.

After 23 days, the distant star began to disappear. What the Chinese saw was the explosion of a star, or a supernova. The energy released by a supernova can destroy a nearby solar system in a few hours. A supernova is one of the highest concentrations of energy in the universe.