Describe the stages in the life cycle of stars from their birth to their death
Similar to a human’s life, stars are born, they live, they evolve, change and then they die. There are a variety of stages in a stars life with the most prominent stages being their birth and death. The life cycle of the star depends on the size of the star. Stars about the same size as our sun follow the left hand path (on the diagram above) of main sequence star, red giant, white dwarf and black dwarf. Stars much larger than our sun follow the right hand path (on the diagram above) of main sequence star, red super giant, super nova, neutron star or black hole. 95 % all stars end up as white dwarfs, and then black dwarfs. The stages in the life cycle of a star will be described in detail below.
STAGE 1: NEBULA
In interstellar space, dust and gas are not evenly distributed, with some regions in the universe containing denser concentrations of swirling dust and gas. When the density of these currents reach a certain density , gravity begins to take control. The causes the gas and dust to collapse into the beginnings of a new star. As it collapses the cloud separates into smaller piece in a nebula cloud, under the influence of gravity. These smaller clouds are visible. The gravitational energy causes the clouds to heat up and the speed causes it to spin. The increasing pressure in the clouds is what causes the temperature rise, which form the perfect conditions for a star to be born.
STAGE 2: PROTOSTAR
During the contraction of the cloud in the nebulae, the material at the centre of the could heats up . The hot core at the centre of the condensing matter starts to heat and glow forming Protostars. The temperature in the protostar causes nuclear reactions in which hydrogen fuses to form helium.
STAGE 3: PRE MAIN SEQUENCE STAR
The protostar accumulates more gas and dust increasing density and temperature. The thermal energy generated, heats up the collapsing cloud and increases pressure within the centre of the star. As star begins to release energy, stopping it from contracting, causes it to shine and become luminous. By now the star would have evolved to a pre main sequence star.
STAGE 5: RED GIANT
The main sequence phase sees hydrogen being turned into helium through nuclear fusion. Through this process, helium begins to build up in the centre of the core and hydrogen forms in a shell around the core of the star. As the helium builds up, the shell begins to swell dramatically in size. In cooling the star becomes a red giant. The red giant creates new heavier elements such as beryllium, oxygen and neon. Through this process the higher rate of energy production causes the stars temperature to rise.
STAGE 6: PLANETARY NEBULA
In the planetary nebula pahse, the outer layers drift away as a gaseous shell. By now the helium core of the star has run out. The gas that surrounds the core is called the planetary nebula.
STAGE 7: WHITE DWARF
After the planetary nebula phase, the star then evolves into a white dwarf. This is very small, hot star. The white dwarf star is the left over remains of stars, where nuclear energy supplies have been used up. White dwarfs stars have very high density due to the gravitational forces. White dwarfs begin to cool and become dim over several billion years.
STAGE 8: BLACK DWARF
A black dwarf is a white dwarf that has cooled so much that it no longer emits heat and light. This stage signifies the death of a star.
Below is a gallery of images displaying the phases of a stars evolution.
Describe the stages in the life cycle of stars from their birth to their death
Similar to a human’s life, stars are born, they live, they evolve, change and then they die. There are a variety of stages in a stars life with the most prominent stages being their birth and death. The life cycle of the star depends on the size of the star. Stars about the same size as our sun follow the left hand path (on the diagram above) of main sequence star, red giant, white dwarf and black dwarf. Stars much larger than our sun follow the right hand path (on the diagram above) of main sequence star, red super giant, super nova, neutron star or black hole. 95 % all stars end up as white dwarfs, and then black dwarfs. The stages in the life cycle of a star will be described in detail below.
STAGE 1: NEBULA
In interstellar space, dust and gas are not evenly distributed, with some regions in the universe containing denser concentrations of swirling dust and gas. When the density of these currents reach a certain density , gravity begins to take control. The causes the gas and dust to collapse into the beginnings of a new star. As it collapses the cloud separates into smaller piece in a nebula cloud, under the influence of gravity. These smaller clouds are visible. The gravitational energy causes the clouds to heat up and the speed causes it to spin. The increasing pressure in the clouds is what causes the temperature rise, which form the perfect conditions for a star to be born.
STAGE 2: PROTOSTAR
During the contraction of the cloud in the nebulae, the material at the centre of the could heats up . The hot core at the centre of the condensing matter starts to heat and glow forming Protostars. The temperature in the protostar causes nuclear reactions in which hydrogen fuses to form helium.
STAGE 3: PRE MAIN SEQUENCE STAR
The protostar accumulates more gas and dust increasing density and temperature. The thermal energy generated, heats up the collapsing cloud and increases pressure within the centre of the star. As star begins to release energy, stopping it from contracting, causes it to shine and become luminous. By now the star would have evolved to a pre main sequence star.
STAGE 5: RED GIANT
The main sequence phase sees hydrogen being turned into helium through nuclear fusion. Through this process, helium begins to build up in the centre of the core and hydrogen forms in a shell around the core of the star. As the helium builds up, the shell begins to swell dramatically in size. In cooling the star becomes a red giant. The red giant creates new heavier elements such as beryllium, oxygen and neon. Through this process the higher rate of energy production causes the stars temperature to rise.
STAGE 6: PLANETARY NEBULA
In the planetary nebula pahse, the outer layers drift away as a gaseous shell. By now the helium core of the star has run out. The gas that surrounds the core is called the planetary nebula.
STAGE 7: WHITE DWARF
After the planetary nebula phase, the star then evolves into a white dwarf. This is very small, hot star. The white dwarf star is the left over remains of stars, where nuclear energy supplies have been used up. White dwarfs stars have very high density due to the gravitational forces. White dwarfs begin to cool and become dim over several billion years.
STAGE 8: BLACK DWARF
A black dwarf is a white dwarf that has cooled so much that it no longer emits heat and light. This stage signifies the death of a star.
Below is a gallery of images displaying the phases of a stars evolution.