What is a Star, How is a Star Born and Die? page all

KOMPAS.com – One of the celestial bodies that often seizes human attention is the star.

Not only visible at night, stars can also be seen during the day.

One of the closest stars to exist in our solar system is the Sun.

So, what is a Star? How is a Star born and then die? What are the types and colors?

Also read: Get to know what a nebula is, the birthplace of stars in outer space

What is Star?

Launch Space, January 4, 2021, Star is any object massive enough to trigger the fusion of elements in its core due to the gravitational pressure within the object itself.

The smallest object known to do so is about 10 percent the mass of the Sun in the Milky Way galaxy.

quote Sky and Telescope, 15 July 2014, star is glowing gas ball. It consists mostly of hydrogen and helium held together by its own gravity.

Nuclear fusion reactions in the core support the star against gravity and produce photons and heat, as well as small amounts of heavier elements.

The sun is the star closest to planet Earth. Meanwhile, the stars seen at night are very far away.

Also read: Get to know Canopus, the Second Brightest Star in the Night Sky

According to current star formation theories, stars are born as clumps in giant gas clouds that collapse on their own. Cloud matter heats up as it falls inward under its own gravitational force.

When the gas reaches about 10 million K (18 million degrees Fahrenheit), the hydrogen core begins to melt into a helium nucleus, and stars are born.

Energy from nuclear fusion radiates outward from the center of the developing star, and gradually stops the gas cloud from collapsing.

Citing a page NASA, stars are born in dust clouds and are scattered throughout most of the galaxy. A familiar example of such a dust cloud is the Orion Nebula.

Three-dimensional computer models of star formation predict that swirling clouds of collapsing gas and dust may break up into two or three clumps.

This explains why most of the stars in the Milky Way are paired or clustered with many stars.

When clouds collapse during the star formation process, a dense hot core forms and begins to collect dust and gas.

However, not all of this material ends up as part of the star. The remaining dust may become a planet, asteroid, or comet or it may remain dust.

Also read: What Is a Black Hole and Can Black Holes Eat The Earth?

Launch Universe Today, January 28, 2009, following types of stars:

1. Protobintang

Protostar is when the star has not yet formed. This is a collection of gas that has collapsed from a giant molecular cloud. The protostellar phase of stellar evolution lasts about 100,000 years.

2. Star T Tauri

The star T Tauri is a stage in the formation and evolution of a star just before it becomes a main sequence star. This phase occurs at the end of the protostar phase, when the gravitational pressure holding the star is the source of all its energy.

T Tauri stars do not have sufficient pressure and temperature at their core to produce nuclear fusion, but they do resemble main sequence stars. The star will remain in the T Tauri stage for about 100 million years.

3. Main Sequence Star (Main Sequence Star)

The majority of all stars in the Milky Way galaxy and the universe are main sequence stars, including the Sun. In addition there are Sirius and Alpha Centauri A.

Main sequence stars can vary in size, mass, and brightness, but they all do the same thing: convert hydrogen to helium in their cores, releasing huge amounts of energy.

4. Red Giant Star

When a star has exhausted its stock of hydrogen at its core, fusion stops and the star no longer generates the outward pressure to counter the inward pressure pulling it together.

The hydrogen shell around the flaming core continues the star’s life, but causes it to increase dramatically in size.

Aging stars have become red giants, and can be up to 100 times larger than their main sequence phase.

The red giant phase of a star’s life will only last a few hundred million years before it runs out of fuel completely and becomes a white dwarf.

Also read: Get to know Sirius, the Brightest Star in the Night Sky

5. White Dwarf Star

When a star completely runs out of hydrogen fuel in its core and lacks the mass to force higher elements into fusion reactions, it becomes white dwarf star.

The outward pressure of light from the fusion reaction stops and the star collapses inward under its own gravity. The white dwarf shines because it was once a hot star, but no more fusion reactions occur.

This process would take hundreds of billions of years, so no white dwarfs have really cooled that far yet.

6. Red Dwarf Star

Red dwarf star is the most common type of star in the universe. These are main sequence stars but they have such low mass that they are much colder than stars like the Sun in the Milky Way.

Red dwarfs are able to keep hydrogen fuel mixed into their cores, so they can conserve fuel for longer than other stars.

Astronomers estimate that some red dwarf star will burn for up to 10 trillion years.

7. Neutron Star

If a star has a mass between 1.35 and 2.1 times the Sun, it does not form a white dwarf when it dies. Instead, the star dies in a powerful supernova explosion, and the remaining core becomes a neutron star.

As the name suggests, a neutron star is an exotic type of star composed entirely of neutrons. This is because the strong gravity of the neutron star crushes protons and electrons together to form neutrons.

If stars were even more massive, they would become black holes after the supernova exploded.

8. Supergiant Star

The largest star in the universe is a supergiant star. This is a monster with a mass tens of times the Sun.

Unlike relatively stable stars like the Sun, supergiants consume hydrogen fuel at an enormous rate and will consume all of the fuel in their core in just a few million years.

Supergiant stars live fast and die young, exploding as supernovae, completely destroying themselves in the process.

Also read: What is the Difference between Asteroids, Comets, Meteoroids, Meteors and Meteorites?

Colors on Stars and their meaning

Still from the page Sky and Telescope, star color depending on the temperature.

The bluer the light that a star displays, the hotter it is. On the other hand, the redder the star is, the colder it is.

Temperature is also correlated with mass. The smallest stars are called red dwarfs.

Red dwarfs have a solar mass of at least 0.075 and a visible surface temperature of less than 4,000 K.

Meanwhile, the most massive star known is R136a1, a Wolf-Rayet star 265 times the mass of the Sun—its visible surface temperature is around 50,000 K.

The most massive (and hottest) stars deplete their energy supply within a few million years, while small, cold red dwarfs can continue to burn for billions of years.

quote Space, Red dwarfs only burn hydrogen weakly in their cores and emit radiation mainly in the infrared part of the electromagnetic spectrum.

Red dwarfs are the most common stars in the Milky Way galaxy, although they are so small and so faint that even their closest neighbor, Proxima Centauri, is completely invisible to the naked eye.

In addition to small stars, there are also medium-sized ones like the Sun in the Milky Way. Such a star is of medium mass, medium brightness, and medium lifetime.

The stars emit radiation across the entire visible spectrum, making them appear nice and white (the Milky Way Sun is also completely white but is filtered through Earth’s blue atmosphere so it appears slightly yellow).

After that, there are giant stars. Because giant stars are very bright, they are easy to spot.

Almost every star seen in the night sky is much larger than the Sun.

For most of their lives, the largest stars are blue. This is because they emit so much energy that the outgoing radiation is actually completely in the ultraviolet, with very little emission coming out in the blue end of the visible range.

Even so, astronomers were confused when they found a strange star. So called because of its large size and red color.

Then a solution was made with the Hertzsprung-Russell diagram, which is the backbone of understanding how stars live even today.

The Hertzsprung-Russell Russell diagram is a plot of a star’s temperature (which can be obtained from its color) and its brightness.

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