SUPERNOVA
Ever wondered whats a Supernova or what do you mean by white dwarf or a red giant? Are these characters from a fairy tale? No, not at all. These are cosmic phenomenon observed and studied and categorized by scientists. Feel like hearing a bit more about it? Then do read on… :-)
Supernovae are massive exploding stars. The explosion occurs at the end of certain star's life time and is so energetic that the resulting illumination can be as bright as an entire galaxy.
To understand why these explosions take place one has to be familiar with the birth and death of stars. A star is born out of a huge gaseous cloud essentially of hydrogen mixed with small quantities of other elements. As the atoms are drawn inwards towards the center due to the pull of gravity, pressure and heat increases. When the core becomes hot enough
to initiate fusion process hydrogen atoms fuse together to form helium and the star is born.
The fusion process then continuous providing the required energy to balance the inward pull of gravity. This phase of the star continuous for a long time. Eventually the supply of hydrogen atoms run down and the fate of the star is sealed depending up on its mars.
Stars up to 1.4 times the mass of the sun (Chandrasekhar’s limit) contracts into a white dwarf star that cools and slowly fades away. Stars more massive can have a complicated death. One possibility is that of a supernova explosion. This is the result of a sudden collapse of a super giant star at least eight times as massive as the sun. Broadly supernovae can be classified into two categories. Type one and Type two.
When the hydrogen reserve is exhausted the gravitational pull gains an upper hand due to the absence of the balancing outward force which comes due to the fusion processes.
The resulting compression of the star will increase the temperature to such a point that helium atoms fuse to form carbon and oxygen. The energy given off again stabilizes the stars until this phase is over. A similar process continues with carbon and oxygen fusing to produce neon, magnesium and oxygen. These elements undergo another fusion process as the temperature and pressure increases to produce silicon and sulphur. The latter two elements then fuse to form iron. Nuclear fusion stops at iron because energy is no longer produced by fusing iron. The star at this stage has a structure that has been compared to an onion. Outside the iron rich core is a layer of silicon and sulphur, then a layer of carbon, neon and oxygen, then a layer of helium and finally an outer region of hydrogen. The iron collapses very quickly. Since the iron core can only collapse and can no longer undergo further fusion it becomes very hot and begins to expand rapidly. Instability is set in when the star core condenses at first and later expands. When the star is collapsing the stars outer shells rush in to fill the void left by the iron core. When the expansion of the core sets in it collides with outer gaseous shells producing tremendous shock waves which glow the outer layers away from the core. This is the supernova’s gigantic explosion. When a massive star undergoes such a fate it falls under the type two category supernova. the heavy elements in the outer skin of the star and those created in the blast wave are scattered throughout space at remarkable initial speed of about 10,000 km/sec. the expanding clouds slows down and dissipates into the inter stellar medium. It also creates the necessary shock waves for new stellar formation.
In a type one supernova two stars are involved. One of them is initially more massive than its companion. It therefore evolves faster and exhausts its fuel quickly. Its inner core is hot enough to initiate the helium and later the carbon fusion while the outer shell is composed of basically hydrogen and energy continuous to be produced there. At this stage instability sets in and the outer layers swell out and as they do so they cool down. This is the red giant phase. The companion now pulls matter from the swelling star, hence becomes more massive and gradually evolves into a red giant, while the other one becomes a white dwarf. The situation gets reversed with the white dwarf drawing matter from the companion. But as its mass increases the limit of 1.4 solar mass the carbon detonates and in a matter of few minutes the white dwarf blows up. The energy released is enormous and the luminosity can reach up to 400,000 million times that of the sun. The expanding gaseous envelope and the inner core the form the super nova remnants.
The supernova explosions are instrumental in redistributing stellar matter in space. The abundance of elements like hydrogen, helium and heavy elements in the solar systems suggest that a blast wave from a supernova explosion could have triggered the collapse of the gas cloud that eventually became our sun.
Disclaimer: The data for this article was picked from an old newspaper article which i do not remember now. All rights are honoured. :)
Supernovae are massive exploding stars. The explosion occurs at the end of certain star's life time and is so energetic that the resulting illumination can be as bright as an entire galaxy.
To understand why these explosions take place one has to be familiar with the birth and death of stars. A star is born out of a huge gaseous cloud essentially of hydrogen mixed with small quantities of other elements. As the atoms are drawn inwards towards the center due to the pull of gravity, pressure and heat increases. When the core becomes hot enough
to initiate fusion process hydrogen atoms fuse together to form helium and the star is born.
The fusion process then continuous providing the required energy to balance the inward pull of gravity. This phase of the star continuous for a long time. Eventually the supply of hydrogen atoms run down and the fate of the star is sealed depending up on its mars.
Stars up to 1.4 times the mass of the sun (Chandrasekhar’s limit) contracts into a white dwarf star that cools and slowly fades away. Stars more massive can have a complicated death. One possibility is that of a supernova explosion. This is the result of a sudden collapse of a super giant star at least eight times as massive as the sun. Broadly supernovae can be classified into two categories. Type one and Type two.
When the hydrogen reserve is exhausted the gravitational pull gains an upper hand due to the absence of the balancing outward force which comes due to the fusion processes.
The resulting compression of the star will increase the temperature to such a point that helium atoms fuse to form carbon and oxygen. The energy given off again stabilizes the stars until this phase is over. A similar process continues with carbon and oxygen fusing to produce neon, magnesium and oxygen. These elements undergo another fusion process as the temperature and pressure increases to produce silicon and sulphur. The latter two elements then fuse to form iron. Nuclear fusion stops at iron because energy is no longer produced by fusing iron. The star at this stage has a structure that has been compared to an onion. Outside the iron rich core is a layer of silicon and sulphur, then a layer of carbon, neon and oxygen, then a layer of helium and finally an outer region of hydrogen. The iron collapses very quickly. Since the iron core can only collapse and can no longer undergo further fusion it becomes very hot and begins to expand rapidly. Instability is set in when the star core condenses at first and later expands. When the star is collapsing the stars outer shells rush in to fill the void left by the iron core. When the expansion of the core sets in it collides with outer gaseous shells producing tremendous shock waves which glow the outer layers away from the core. This is the supernova’s gigantic explosion. When a massive star undergoes such a fate it falls under the type two category supernova. the heavy elements in the outer skin of the star and those created in the blast wave are scattered throughout space at remarkable initial speed of about 10,000 km/sec. the expanding clouds slows down and dissipates into the inter stellar medium. It also creates the necessary shock waves for new stellar formation.
In a type one supernova two stars are involved. One of them is initially more massive than its companion. It therefore evolves faster and exhausts its fuel quickly. Its inner core is hot enough to initiate the helium and later the carbon fusion while the outer shell is composed of basically hydrogen and energy continuous to be produced there. At this stage instability sets in and the outer layers swell out and as they do so they cool down. This is the red giant phase. The companion now pulls matter from the swelling star, hence becomes more massive and gradually evolves into a red giant, while the other one becomes a white dwarf. The situation gets reversed with the white dwarf drawing matter from the companion. But as its mass increases the limit of 1.4 solar mass the carbon detonates and in a matter of few minutes the white dwarf blows up. The energy released is enormous and the luminosity can reach up to 400,000 million times that of the sun. The expanding gaseous envelope and the inner core the form the super nova remnants.
The supernova explosions are instrumental in redistributing stellar matter in space. The abundance of elements like hydrogen, helium and heavy elements in the solar systems suggest that a blast wave from a supernova explosion could have triggered the collapse of the gas cloud that eventually became our sun.
Disclaimer: The data for this article was picked from an old newspaper article which i do not remember now. All rights are honoured. :)
posted by Sanoop at 9:31 PM
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