20 Jan 2019

Nebula "The birth place of stars"!

Nebula "The birth place of stars"

Nebulae

The night sky ,how beautiful it looks and has also too many mysteries in it. If we talk about it's beauty, then stars are the objects that makes it so beautiful by forming such a beautiful arrangements called constellations and have different colours and are at different distances. And also stars are the only energy source of universe. As we know that everything that are in the universe born and has to die. In the case of stars the place where they born called Nebula. But, nebula is not a only place where they born but we can say stars mostly born in nebula.
Lets know more about Nebula........

What is Nebula?

As we know many bodies are present in space like stars, planets, black holes and Nebula is like one of them. Nebula are giant cloud of dust, hydrogen, helium and other ionized gasses in space.

How big is Nebula?

If we talk about size of nebula then most of nebulae are of vast size and some are hundreds of light years in diameter. A nebula that is barely visible to the human eye from Earth would appear larger, but not brighter. The Orion Nebula is the brightest nebula in the sky and occupying an area twice the diameter of the full Moon and can be viewed with the naked eye.

Where are Nebula present?

Nebulae are present in the space between the stars which is also known as interstellar space. And the closest known nebula to the Earth is called the Helix Nebula, which is remnant of a dying star possibly one like the Sun. It is approximately 700 light-years away from the Earth.


Types of Nebulae

1. Diffuse Nebulae

As we all know that word diffuse means spread out. 

Now guess how does diffuse nebulae appears?

If you guess that they are very large in size and spread out then you are absolutely right. Actually the dust and gas of diffuse nebulae are often so spread out that it’s hard to tell where the nebulae start and where it ends. That means diffuse nebula has no well defined boundaries.

Diffuse Nebulae can also be divided into :-

i. Emission Nebulae

As it is a type of diffuse nebulae so are very large and are often birthplace of stars. One of the well known is the Orion Nebula.
Emission Nebulae

Emission nebulae usually glow red or pink in colour. This is because they contain lots and lots of hydrogen gas. Hydrogen gives off red light when it’s energized! Hey guys if you don’t like red or pink colour, lets see next nebula that we are going to talk about.

ii. Reflection Nebulae

Sometime nebulae don’t have stars with enough energy to excite the gas of nebula. At this stage they reflects light of nearby stars.
Reflection Nebulae

As you notice small particles of dust floating in the air. And we all know this happen because dust particles reflects the light. This is what pretty much happens in reflection nebula.
As i told you about colour reflection nebula often appears blue as we look it from telescope.

iii. Dark nebulae and Bok Globules


As you can probably guess, Dark nebula don't emit or reflect any light because gas and dust in dark nebula is very thick.
Dark nebulae

Astronomers can see dark nebulae when they’re in front of something bright. Dark nebulae block out light from emission nebulae and stars behind them.

Bok globules are small dark nebulae. Like in emission nebulae, stars can form in Bok globules! Because the gas is already so dense, gravity pulls harder on it until it collapses to form stars.



2. Planetary Nebulae

That’s not the end of our tour  – there’s some more nebulae! Next, there are planetary nebulae. Despite their name, these shells of gas have absolutely nothing to do with planets! They earned this name because early astronomers thought they looked like giant planets.
Planetary nebulae

Planetary nebulae are form when a star runs out of fuel to burn. As they get old, stars like our sun change into a red giant star. After spending millions of years as a giant, the star shrinks again, pushing off outer layers of gas. These layers of gas form planetary nebula! Examples are the Cat’s Eye, Butterfly, and Engraved Hourglass Nebulae.

Planetary nebula are visible for around 50,000 years, so there’s plenty of time to get out your telescope. Maybe you can decide for yourself if it looks like a planet!

3. Supernova remnants

Supernova remnant

When a high mass star reaches the end of it’s life, it can explode. This explosion is called supernova. This explosion produces a cloud of gas and dust, which becomes a nebula known as a supernova remnant.
In supernova remnants, the gas becomes energized from the explosion, so it also emits light! Supernova remnants also give off lots of x-rays and radio waves. One example of this type of nebula is the Crab Nebulae.


Formation of star from nebulae

As we know stars are form in nebulae, so lets know how they actually forms.

So the Stars are born within the clouds of dust and scattered throughout most galaxies. A familiar example of such as a dust cloud is the Orion Nebula. Turbulence deep within these clouds gives rise to knots with sufficient mass that the gas and dust can begin to collapse under its own gravitational attraction. As the cloud collapses, the material at the center begins to heat up, known as a protostar, it is this hot core at the heart of the collapsing cloud that will one day become a star.

As the cloud collapses, a dense, hot core forms and begins gathering dust and gas. Not all of this material ends up as part of a star,  the remaining dust can become planet, asteroids, Comet and even remain as dust.

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