White Dwarf
Hey! Welcome back to my blog! Have you heard
about a white dwarf in space?
Probably yes! You might have heard the recent news that astronomers have discovered a
star that is as small as a moon but with more mass than the sun. This star is
a white dwarf!!
Now, are you more curious about it?
A low or medium mass star (with a mass less than about 8 times the mass of our Sun) will
become a white dwarf. The Burned-out core of a star is a white dwarf. Let’s take
an example of our sun to understand what white dwarfs are and how they are
formed.
Formation of a white dwarf:
Our sun produces heat, for producing heat they need fuel. So like how we use LPG or
diesel for fuel, our sun uses hydrogen and helium as its fuel.
The actual process taking place is a fusion of hydrogen with heat to give helium.
HYDROGEN FUSES WITH HEAT HELIUM
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This heat energy and gravitational energy are balanced. It’s like the tug of war game
where our sun is in the center, where gravity pulls it inwards and heat pulls
it outwards. This energy given by both of them is equal causing our sun to be
stable.
But a time will come when the amount of hydrogen present will get reduced so this
balance is disturbed; now the gravity is giving high energy, so the sun will
start compacting.
This process gives off heat. Now our sun will use that heat to fuse with a little
amount of hydrogen present. Then, the heat slowly gains momentum. Now, the sun
will grow bigger than its normal size; it may even swallow mercury. This causes
our sun to become a red giant.
Now the heat present is high but when it is growing at a very fast rate the overall
temperature drops down. Plus not to forget the amount of hydrogen is reduced.
At one point in time hydrogen will be completely used. So the sun will now be filled
only with helium. And the overall temperature is also low.
Now, what happens? Any guess??
Yes! Again gravity wins pulling the sun towards it; this process causes heat. Our
sun uses this heat to fuse the helium into carbon.
HELIUM FUSES WITH HEAT CARBON
So now again it expands but this time larger than the red gain it will definitely
swallow our EARTH!
So now helium is also used. What will happen? It follows the same process, it gets
compressed and produced heat expanded but this size is larger than what we had
earlier. So again the overall temperature is decreased.
Carbon does not fuse with heat to give some gas or fuel. So when the amount of carbon
present decreases our sun becomes very unstable, it will start losing masses.
At one particular point in time, the outer layer would be completely gone!
With the star now being very compressed, dense with no fuel it turns into a white dwarf.
At the beginning of the white dwarf, they will be hot but slowly they will lose
all their heat. No longer emitting heat or light, the white dwarf will become a
black dwarf. Because it emits no radiation, it is nearly impossible to see. ...
Scientists have calculated that a white dwarf will take at least a hundred
million billion years to cool down and become a black dwarf.
Therefore we can conclude that the burned-out core of a star is a white dwarf.
White
dwarf stars, so-called because of the white color of the first few that were
discovered
The white dwarf will be surrounded by an expanding layer of gas known as planetary
nebula. Nebulas are clouds of gas and dust. A planetary nebula is a type of nebula. They are hardly related to planets,
not even close but they got their name because of their huge appearance like
planets.
Characteristics of a white dwarf are:
1. Low luminosity
2. Dense
3. Low temperature
4. Visible radiation emitted comes in a wide color range.
So, now we know about the white dwarf.
Stay tuned for the next journey!
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Good one!! Very informative.
ReplyDeleteThank you so much!
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