Understanding Nebulas-Enigmatic Clouds Of Dust & Gas
- Ananya Sharma
- May 9, 2024
- 3 min read
Hello, Everyone!
Our universe is home to many enigmatic entities such as cosmic dust, cosmic matter, planets, moon, stars, nebulae, galaxies, black holes, and many more each possessing their mysteries and characteristics.
One such enigma is Nebulae{plural of nebula}.
But what is a Nebula and where does it exist in the universe?
A nebula is a massive cloud entailing cosmic dust and gas amid the stars{mainly hydrogen}existing in interstellar space- the space between the stars. The HELIX NEBULA is the nearest nebula to our earth, and is 700 light years away from our EarthThis implies if we travel through light's speed then also, it will take 700 years to reach the Helix Nebula.
Nebulae is of the following types:-
-> 1. Bright Nebula/Glowing Nebula/Emission Nebulae
-> 2.Dark Nebula/Absorption Nebula
->3. Planetary Nebula
->4. Supernova Remnant
BRIGHT NEBULA: Nebulas that glow with their light significantly made up of gas are called Bright Nebulae. In contrast, the other nebulae created from dust are denser and hinder the passage of light through them which might be coming from far-away cosmic entities such as stars and are referred to as dark nebulae.
DARK NEBULA: These are also called Absorption nebulae, they are dense clouds of dust clouds and are opaque because of the dust particles they consist of. In this nebula, the hydrogen is in its molecular form i.e. H2 molecules. These massive clouds have colossal masses- a millionfold greater than our sun's mass. They can extend up to large distances-150 light years from our Sun. These are the vital components of the interstellar medium and consist of significant hydrogen gas. The central region or the cores of these massive molecular clouds are curtained from optical observation by dust particles. The feeble microwave radiation released by these H2 molecules is observed by the telescopes that are not hindered by the dust grains. Therefore, in this way, the dark nebulae are detected. The cloud cores are immensely dense- the densities can be up to 10^5 hydrogen molecules (H2) in one cubic centimeter which is approximately hundredfolds dense as compared to the average cloud environment.
PLANETARY NEBULA: These are referred to as gas and dust emanating from a dying star. However, these have a shorter life span. Stars up to an intermediate mass swell to form a red giant. The red giant expels its outer layers made up of gas and dust into space. The left-out core heats up and emits UV rays. This radiation when collides with the expelled gas atoms rips a gaseous atom off an electron, thus a cation is formed as a positive ion. {a process called ionization}These positive ions are in search of stability and regain electrons by emitting photons of light. This emitted light is what we see as glowing light.
SUPERNOVA REMNANT: These are clouds of dust and gas formed from the explosion of a collapsing star a supernova explosion, along with a shockwave that glides through the nearby interstellar cosmic dust and gas. This collapse left out dust and gas glowing with radiation from the explosion is called a Supernova remnant.
STAR FORMATION THROUGH NEBULAE: But how do nebulae play a vital role in star formation?
The cosmic dust and interstellar gas in the nebulae are dispersed at distant sites. However, gravity pulls these clusters of gas and dust with each other making these clusters gigantic thereby possessing a very potent gravitational pull. Thus these clusters of gas and dust become extremely dense and thus the atoms collide with each other at increased speeds. Thus friction is created which converts the kinetic energy of these particles into thermal energy. Hence the core heats up with large temperatures. This high density and temperature is ideal for fusion reactions to start which marks the birth of a star. The outward pressure from nuclear fusion ultimately evens out the inward gravitational pull and henceforth a stable star is formed.
How can we see these nebulae?
Very powerful space telescopes equipped to capture and analyze the radiations emanating from nebulae with a technique called spectroscopy -can detect nebulae. For instance NASA's Spitzer Space Telescope and Hubble Telescope.
Conclusively, we can say that nebulae are enigmatic cosmic clouds of dust and gas that play a vital role in the formation of stars and they emanate beautiful radiations of colors.
Thank You.
References :
An informative article that explores the awe-inspiring beauty and scientific significance of nebulae. It is a captivating read for anyone intrigued by the wonders of the universe.