Astronomy

Life Cycle of a Star

Life Cycle of a Star

We all have seen the bright and shiny stars in the night sky. But, we do not know anything about the life cycle of a star. In this topic, we are going to overview the life of a star.

Meaning of Stars

Stars are a large ball of plasma that without doubt fills the space around them with heat and light. Moreover, they came in a variety of masses, and their mass decides how hot the star will burn and how they will die.

Also, heavy stars turn into a neutron star, black holes, and supernovae. On the other hand, average stars like sun end their life as white dwarf surrounded by disappearing planetary nebula.

However, all stars roughly follow the same basic seven-stage life cycle, starting as a gas cloud and ending as a star remnant.

life cycle of a star

Life Cycle of a Star – Step by Step Explained

1. Giant Gas Cloud

The life cycle of a star begins as a large gas cloud. Also, the temperature inside the cloud is low enough that a molecule can form in it.

Besides, some molecules such as hydrogen light up and allow astronomers to see them in space. Moreover, the Orion Cloud Complex of the Orion System can be the nearest examples of the star in this stage of life.

2. Protostar

It is a baby star that forms when gas particles in the molecular cloud run into each other, and they create heat energy.

Furthermore, this allows a warm clump of molecules to form in the gas cloud. Besides, this clump is well-known as Protostar.

While protostars are warmer than other materials in the molecular cloud so they can be seen with infrared vision. In addition, depending on their size there can be several protostars in one cloud.

3. T-Tauri Phase

A young star starts to form in the T-Tauri phase and it begins to produce strong winds that push away the surrounding molecule and gas.

Moreover, it allows the forming star to become visible for the first time. Besides, scientists can spot the star in the T-Tauri phase without the assistance of radio waves and or infrared.

4. Main sequence star

In this stage, the young star reaches hydrostatic balance and its gravity compression is balanced by its outward pressure, giving it a solid shape.

After that, the star becomes a Main Sequence star. Also, it spends 90% of its life in this stage fusing with hydrogen molecule and forming helium. Most noteworthy, the sun is currently in this stage.

5. Expansion into Red Giant

When all the hydrogen is converted into helium then the core collapses on itself that causes the star to expand. On expansion firstly it becomes a sub-giant star and after that the Red Giant.

It is cooler than the main-sequence star and that’s why it appears red and it can become large enough to be a supergiant.

6. The fusion of Heavier Elements

While expanding star begins to fuse with helium molecule in its core and this reaction prevent the core from collapsing. After helium fusion ends, the core shrinks and star start fusing carbon.

Moreover, this continues till iron starts appearing in the core. Iron fusion absorbs energy and causes the core to collapse.

If the star is massive enough then the implosion create supernova while small stars like sun contracts into white dwarfs whereas their outer shell radiate away as planetary nebulae.

7. Supernovae and Planetary Nebulae

Supernova explosion is the biggest events in the universe. Furthermore, most of the material blows away but the core implodes rapidly into a neutron star or a singularity known as a black hole.

While small stars don’t explode ad contract into tiny hot stars called white dwarfs while their outer material drifts away. Moreover, astronomer’s suspects some red dwarf have been in their main sequence since shortly after big bang.

Solved Question for You

Question. Which is the largest star in the sky?

A. OGLE-TR-122b,
B. VY Canis Majoris
C. Red giant
D. Blue giant

Answer. The correct answer is option B.

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