Exploring the High Density of White Dwarfs: A Question of Temperature?

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In summary, white dwarfs are compact stars with a very high density due to the packing of electrons near the nucleus, known as degenerate matter. This density is not due to cold temperatures, but rather the force of gravity. They are located in the bottom left of the Hertzsprung-Russel diagram with low absolute magnitude and luminosity, but high surface temperature. This is because in order for the electrons to be packed tightly near the nucleus, the temperature must be extremely high, around 10 million kelvin. When a star exhausts its fuel and can no longer sustain this high temperature, it begins to contract and cool, becoming a white dwarf. Despite being very hot, white dwarfs can still contract because they do not
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A white dwarf about the size of the Earth but with a mass of a star leads to a very high density. An atomic structure where the electrons are packed very close the the nucleus, otherwise know as degenerate matter. Correct me if I'm wrong; this is due to cold temperatures. Then how come white dwarfs are located the bottom left of the Hertzsprung - Russel diagram marked with low Absolute Magnitude and lumosity but high surface temperature? In order for electrons to be packed tightly near the nucleus wouldn't the temperature have to be near 0 Kelvin?

Thnx

Sorry I don't have a link for the HR diagram, I'm getting it from a book.
 
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DB said:
A white dwarf about the size of the Earth but with a mass of a star leads to a very high density. An atomic structure where the electrons are packed very close the the nucleus, otherwise know as degenerate matter. Correct me if I'm wrong; this is due to cold temperatures...

DB the high density is not due to extreme cold, but rather to gravity


what keeps our sun from contracting to small size is the temperature at the core which is about 15 million kelvin.
(much more than the roughly 5000 kelvin at the surface!)

something 15 million kelvin glows Xrays, not ordinary light

the core MUST be this hot to create outwards pressure to fight against gravity.

when a star exhausts all the fuel, can no longer fuse nuclei, can no longer sustain the high (millions kelvin) core temp, then its core begins to cool and it begins to contract

(along the way there can be episodes where it can fuse other elements and temporarily re-expand, so it may not be a straight line decline)

You are right to study the HR diagram, the story of many stars is shown there.

The star can contract and become dwarf-dense even tho it is very hot!

It can be white hot. It can be 100s of thousands kelvin!

It can still contract, even tho very hot, because in its core it does not have the 10 million kelvin (or so, more or less) needed to keep in an expanded state.

so white dwarves can be hot and stay hot for a long time (gradually cooling as they radiate away their high temperature heat)

because they are so compact, have little surface area compared with mass, they cool slowly

probably someone will supply a link that says all this better. I have to go so no time to get a link
 
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Wow perfect explanation thanks, apreciate it
 

1. What is a white dwarf?

A white dwarf is a small, dense star that is the remnant of a low or medium mass star after it has exhausted its nuclear fuel and shed its outer layers. It is typically about the size of Earth but contains a mass similar to that of the Sun.

2. How does a white dwarf form?

A white dwarf forms when a star with a mass less than 8 times that of the Sun runs out of nuclear fuel. The star will then shed its outer layers and the core will collapse, resulting in a small, dense white dwarf.

3. What is the high density of white dwarfs?

The high density of white dwarfs refers to their extremely compact size and high mass. A white dwarf can have a density of up to 1 million times that of water.

4. Why are white dwarfs important to study?

White dwarfs are important to study because they provide insights into the evolution of stars and the fate of our own Sun. They also serve as laboratories for studying extreme conditions and can help us understand the behavior of matter under high densities.

5. Can white dwarfs become black holes?

No, white dwarfs do not have enough mass to become black holes. In order to become a black hole, a star would need to have a mass of at least 3 times that of the Sun. White dwarfs have a maximum mass of about 1.4 times that of the Sun, known as the Chandrasekhar limit.

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