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| Life Cycle of Stars |
Let
me invite you to visit the wonderful world of interstellar environment, our
science has advanced very deeply in to cosmology with the invention of advanced
telescope.
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| Star Explosion |
The
primordial atomic element of the universe were hydrogen and helium .These light
elements are able to make a star .For life to be possible heavier elements such
as carbon , oxygen and nitrogen are required ,these elements are forged inside
nuclear furnaces of the first generation stars. When these first generation
stars die they disperse most of their mass in to space, these dust and gas of
exploded stars assemble to form nebulae.
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| Protoplanetory disc- Protostar |
Sudden
explosion of some nearby stars produces ripples across through clouds, stirring
the gas and dust particles, with sufficient gravitational attraction they clump
together and interact. This interaction cause it to spin faster and as these
dense clouds spin it flatten in to disc, Within 10 million years the center of
disc become protostar and after 20 million years the disc around the protostar
become protoplanetory disc .Our earth began from the grains of dust in the
whirlwind of protoplanetory disc, and in time coalesced to form the planet gathering
all the elements required to make the ecco system necessary for life. A star
cannot be formed unless the planets picks up most of its angular motion of the
whirling dust cloud.
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| Eagle Nebulae |
Total
125 billion galaxies are known to us and each has 100 billion stars. The famous
nebulae eagle which is 400 trillion miles hurled and 300 trillion miles wide
has been made by materials blown in to space from exploding stars. As gravity
pulls the raw materials in on itself large balls form at the center of each
clouds these are the protostars, they are covered with a dense cloud that is
blowned away by the heat produced in the contracting protostar at the core of
the ball the heat increases due to collision between dust particles and
intensify with continuing contraction , when the core temperature become 10
million degree centigrade nuclear fusion of hydrogen to helium begins
with fusion energy is released as light .The size of stars depend upon the
amount of gas and dust gathered during its formation. The brightest super star
is 150times bulky as the sun and smallest star is 10 times less massive than
sun. Smaller stars are dim but they live longer than big stars.
Heavier
protostars contract quicker to form stars compared to smaller ones .Being a
star is a balance act between contraction and expansion. The force of gravity
is attracting every part of star to the center, while the huge fusion energy is
pushing everything outward. A stable star has both these force balanced. The
balance is maintained if there is sufficient hydrogen available in star.
When
this hydrogen is depleted, gravity wins the battle and star starts to collapse,
gravity cause the star to contract, this gives the star a second chance to
survive by fusion of helium in to carbon, in stars the heavier elements are
formed in this process. In this process nuclear fission occurs to hydrogen gas
surrounding the outer star shells which cause the outer envelope to expand as a
result of energy released from nuclear fusion, the core on other hand contracts
and radiation energy inside will increase causing the outer shells to expand
further more and the star start to glow brighter than ever, As the temperature
starts to decrease in expanding envelope the color shifts to Red making the
star a RED giant.
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| Red Giant |
Like sun after
becoming a red giant, finally gives its outer shells to universe in the form of
planetary nebula, as this envelope casts off the core of sun become smaller
like earth we call it white dwarf. It’s so dense that one teaspoon of its core
weighs 5 tons on earth. The tightly compressed electrons produces a quantum
repulsive force which balances the gravitational pull inwards, it radiates its
remaining trapped energy which creates a beautiful glow , it loses its light
over billions of years to form cold black mass then we call it black dwarf.
In big stars are hungrier and go through their fuel much
faster, once all the hydrogen at the stars core has fused to become helium its
starts to become super red giant, its core shrinks to create heavier elements
resembling like onion shells, eventually making its central core with iron
where the core temperature reaches to 5 billion degrees or more. Iron cannot
burn to form energy to sustain nuclear fusion. The gravitational push is first
balanced by quantum repulsion of electrons , but strong gravitation force
squeezes the electrons in to nucleus to form neutrons , with loss of electron
nothing is there is oppose the push of gravity as result gravity crushes the
iron core from say size of earth to twenty kilometers in diameter , where
quantum repulsion of neutron resists further compression .This core collapse
releases enormous amount of energy , we call the exploding star supernova
.These shock waved caused by the explosion of core can travel at speed as much
as 30,000 miles per second pass through the shell of gas surrounding the core
generating temperature and pressure highly enough to create elements heavier than
iron . The outward layer consist of carbon , oxygen , nitrogen and silicon
blast themselves in to space at speed up to 10,000 miles per second these
elements are the building blocks of life in earth.
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| Supernova |
The
resulting supernova comprises of 95 % of destroyed star, its brightness rises
to a maximum and then fading all happening in a weeks or months’ time.
The elements thrown out from expired stars form giant molecular gas cloud like
eagle nebula, as these clouds are the nurseries where new solar systems are
born. It is very likely that the birth of our solar system was initiated by the
disturbance created when the shock waves from a nearby passed through the lanes
of gas and dust in a spiral arm of our galaxy.
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| Inside a neutron star |
Neutron
star is the densest object in the universe , one spoon of neutron star will
weigh millions of tons on earth and it spins at incredible speed like 716 times
a second , due to its intense magnetic fields it radiated a narrow beam of
electromagnetic radiation which falls in the range of radio waves , its
directed beam sweeps through space like a light house beacon, if earth happens
to be in the path of radiation , a pulsed radio signal is detected as if coming
from a transmitter in space, they are otherwise called pulsars.
In
big stars twenty five times larger than sun , since its initial mass is larger
the gravitational pulls overwhelms the repulsive force of neutron and its
entire mass is squeezed instantly in to a space smaller than the head of the
pin actually much smaller than the nucleus of a single atom. How dense such an
object would be , how much gravitational force will it exert , so much that
even light could not escape it .that why we call it black holes. The black hole
is like a cosmic sink hole sucking all the surrounding materials in to its
center, as stars and planets happens to be near to black hole are drawn in to
the vortex they begin to spin around forming accretion disc, it become so hot
and stars in its starts to radiate light, allowing us to observe the materials
inside before it is swallowed in.
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| Mass of star vs star final form |
Giant
black hole compact accretion region emit light even from 10 billion light years
we can see their light .The black hole at our center of galaxy is called by
name Sagittarius A and its mass is roughly 3.7 million times sun every second
100 supernova explosions are happening in universe.
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| Binary Stars rotating mechanism |
Binary star ,
orbit one another , if one of the pair become white dwarf its gravity can
withdraw matter from companion star ,when a white dwarf mass become 1.5 times
larger than that of sun it explodes as supernova, nothing remain behind. The
entire mass of star is blown to space.
Now we have seen
the universe doesn’t waste anything, for each star dies another is born .the
cosmos conserve and recycle long before people did. The energy required for
this process was there and remains there forever, and what is the power source
for the universe?
