The Universe- Stars
A star is considered as a celestial and astronomical object, which is luminous due to the presence of plasma- which is the fourth state of matter and has the gravity of its own. This can be considered as the formal definition of the stars, now we shall discuss it further.
BIRTH OF THE STAR,
Nebula a gaseous cloud; according to the most appropriate theories, stars born under the incredibly high density of this cloud, which later by time condenses, which takes billions of years and starts contraction towards the centre, by its own self made gravity. The perfect example of this cloud is the ORION NEBULA, which is just visible with our naked eyes, during summers when the sky is clear. The gases and the clouds of dust get collected as a clump. Each of these clumps starts getting together by the nuclear reactions which released heat energy, nearly 12 million degree Celsius!
You would love to see the stars at the night, the dark sky and the shining many dots in it. Some would appear to be shining brightly and some appear to be dull. Lets us now know some names of the brightest stars are ever known to us.
Some of the brightest stars known to us are as follows-
- SIRIUS, THE DOG STAR, blue-white dwarf in constellation CANIS MAJOR.
- CANOPUS, yellow-white supergiant in the constellation CARINA.
- ALPHA CENTAURI, triple star in the constellation ‘Centauris’.
- ARCTURUS, orange coloured giant in the constellation BOOTS.
- VEGA, a blue dwarf in the constellation LYRA.
- CAPELLA, four star cluster in constellation AURIGA.
Now, here is the top 10 brightest star ever known to us-
- Rigil Kentaurus
HOW THE STARS ARE BEING CLASSIFIED?
Stars are being classified on the basis of their-
The size of the star generally means its mass or volume, not its diameter or volume. However, some of the celestial bodies are measured by its diameter and volume.
The rest of the three points, the temperature, colour and the luminosity are interlinked to each other. The temperature of the hot stars like the Rigel is about 15,000 k. Some of the cool stars’ temperature may range from 2,000 to 8,000k. Whereas, the colour and luminosity depend upon their temperature itself. Very hot stars emit blue rays which are the most luminous of all. Medium hot stars emit white colour and are having moderate luminosity. The dull stars appear to be red or orange in colour and are relatively coolest among stars. But size matters in the lifespan of the star. Small stars continue to burn for hundreds of billions of years. The largest star about the thousand times the mass of the sun, live a shorter life, burning out after a few million years and dying with a bang. They become exploding supernovae that may leave behind the remnant of glowing gas. Shockwaves from the supernovae tend to compress interstellar gas, which may ignite and become a new star, called stellar recycling.
SOME IMPORTANT KEYWORDS,
LIGHT YEAR, the distance travelled by light moving in a vacuum in the course of one year, as its the accepted velocity of 186,283 miles per second, or 298,053 km per second, used as a unit to identify the distance between celestial bodies, in the universe.
NEUTRON STAR, a body of densely packed neutrons, formed after the explosion of a supernova.
“A neutron star of 10 miles in diameter could have more mass than the three stars comparable in the size to our sun.
SUPERNOVAE is the violent, luminous explosion at the end of a massive star’s life.
THE STAR DEATH
Majority of the stars take about millions of years to die. Let us take the example of the sun, then if it had burned up or had used up all of its hydrogen fuel, then by the time it starts to become a red giant. This may engulf mars or even asteroid belt. After it had expanded it would collapse to form a very dense white dwarf. The cooling process of the white dwarf will remain continued for millions of years and would become invisible. This means that it would become a small black hole. The white dwarf is so dense that one tablespoon of the material
will weigh around 500 tonnes. Bigger stars do the same thing but after becoming a red supergiant, it will blow up in huge supernovae explosion. The supernova shines brightly around the galaxy. Then it quickly fades away and turns into a neutron star, simply a black hole.
Lastly, the biggest star ever known to humans is the VY Canis Majoris. But some too believe that its UY Scuti. In comparison to these two, our solar system is a small unit particle of dust.
I hope you have enjoyed reading this article will come up with the next very soon.
Written & created by-
AND SPECIAL THANKS TO
Koushik Mishra (editor & head)