Hi Everyone! This is Ramesh here and today
we will know about one of the most fascinating
space objects known as a star.
We see around 5,000 stars in the sky which
is just a tiny drop in a cosmic ocean. It
is estimated that our universe has more than
1 quadrillion or septillion number of stars
that is one followed by 24 zeroes.
Our Sun is also a star and it appears big
from others because it is the nearest star
to earth.
In the following animation we will see some
of the neighbouring stars and how much time
voyager-1 will take to reach there if aimed...
Star is a hot ball of plasma held together
by its own gravity. Stars are born inside
hydrogen-based dust clouds called nebula.
When the hydrogen clouds collapse due to gravity,
material at the center begins to heat up,
as a result, a Protostar is born. Protostar
is a very young star that is still gathering
dust and gas from its molecular cloud.
For a star like our sun, this protostellar
phase lasts about 500,000 years.
As the compression of hydrogen gas continues,
the core becomes so hot that the process of
nuclear fusion starts, where hydrogen atoms
fuse to form helium. In this process, some
matter is lost which is converted into energy
and a star is born. This relation of matter
and energy was discovered by Albert Einstein
by his famous formula E=mc^2. Where E is energy,
m is the mass and c is the speed of light.
Stars are stable for billions of years because
the inward pull of gravity is balanced by
the outward pressure of gas heated by fusion
and this balance is called hydrostatic equilibrium.
In its lifecycle, it creates basic matter
from which everything in the universe is made
including planets, moons, even life.
Stars can be lonely like our sun and form
pairs, multiple systems and star clusters.
Stars burn in different colors depending upon
the surface temperature from red, orange,
yellow, white, blue.
Morgan-Keenan system is used to classify stars
the hottest “O type” to the coolest “M
type”
The upcoming video shows the size of stars
and also provides details and its distance
from the sun in light-year. A light-year is
an astronomical unit equivalent to distance
traveled by light in one year. 1 light-year
= 9,461,000,000,000 Km (9.461 trillion km)
Don’t forget to like, share, comment and
subscribe. Thanks for watching!
When the star consumes all the hydrogen in
its core, nuclear fusion reaction suddenly
stops. Due to which core collapses into itself,
as no more energy is produced to counter the
inward gravitational force.
Still, there is Hydrogen available outside
the core so hydrogen fusion continues there.
As the core of the star getting hotter and
hotter it pushes the outer layers of the star
outwards, resulting in the expansion of outer
layers. Due to expansion, the star is now
transformed into a red giant star.
With no hydrogen left to fuel it, the star
begins fusing helium into carbon which generates
a humungous amount of energy waves which slowly
disintegrate the star and finally only the
intensely hot stellar core is left, and now
the star is transformed from red giant to
white dwarf star. At this stage, the nuclear
fusion process stops and star dies.
A white dwarf is about the size of the earth
but has the mass of a star. Our sun will also
undergo the same lifecycle and eventually
become a white dwarf...
An average star like our sun lives for billions
of years. The more massive the star the less
its lifespan.
In the next animation, we will look into the
Hottest, coolest, Most and least massive stars.
Let’s get right into it…
When a
star is massive the core temperature goes
high enough to fuse Helium and produce heavier
elements up to iron. In nuclear fusion process
elements heavier than iron consumes energy
instead of producing, due to which the star
no longer counter the inward pull of the gravity
resulting in the collapse of the iron core.
At this stage, the core temperature exceeds
100 billion degrees which happens in seconds.
Star outer layers along with its core, collapse
and bounce back with an enormous explosion
known as a supernova. Supernova can outshine
entire galaxies and generate an unbelievable
amount of energy which is even more than what
our sun will give in its entire lifetime.
Stellar core with mass ranging from 1.4 to
3 solar mass collapse, as gravity is so strong
that electrons and protons combine to form
neutrons giving birth to a neutron star. On
the other hand, if the core is larger than
3 solar mass it collapses entirely and becomes
a black hole.
For more details on the black hole, you can
watch “Black Holes - the end game” video
on the channel.
In this last segment of the video, we will
look into smallest, largest, brightest and
variable stars in the universe. Let’s see…
