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NEBULA - THE NURSERY OF STARS


Nebula is a stellar object which is also known as the ‘star nursery’ (birth place of stars).  The nebula was first recorded by Ptolemy in his book ‘Almagest’ around 150 AD. With the parallel advancement in optics, several nebulae were observed and reported.

What is Nebula:

  • Our universe is filled with random gas and dust particles which are collectively known as Interstellar Medium (ISM). Nebula is a spot where a giant cloud of dust and gas in space.
  • More than one nebula is known as nebulae. It is originated from a Latin word ‘nebula’ which means “mist, vapour, fog, smoke, exhalation”.

Birth of Nebula:

  • Some nebulae are formed by gravitational collapse of interstellar medium
  • Some nebulae are formed by supernova explosion.

Types of nebula:

Nebula is classified into four types.

  • Diffuse Nebulae: Most of the nebulae fall under this category and it is further divided into two categories based on their response to the visible light.
   1.Emission nebulae: They are largely composed on ionized hydrogen and emits spectral line    radiation
    2.Reflection nebulae: They won’t emit visible light, but will reflect the light from the nearby sources like stars.

  • Dark Nebulae: They neither emit or reflect the visible radiation. They will emit radiation in infrared region.
  • Supernova Remnant Nebulae: It is formed by the supernova explosion (death of the stars).
  • Planetary Nebulae: Some red giants will lose their outer layers and emits ions in their surroundings during the final stage of the stars.

Notable nebulae discovered: Eagle nebula, Helix nebula, Pelican nebula, Orion nebula, Rosette nebula, Boomerang nebula.


  Helix Nebula
     Credits: NASA, ESA and the Hubble Heritage Team 

    References:

  • https://spaceplace.nasa.gov/nebula/en/
  • https://spacecenter.org/what-is-a-nebula/

                                                              

                                 



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