The final evolutionary state of stars whose mass is not high enough to become a neutron star or black hole.
Questions tagged [white-dwarfs]
77 questions
22
votes
1 answer
Why are there no known white dwarfs between 1.35 to 1.44 solar masses?
The Chandrasekhar limit for white dwarfs is 1.44 Solar masses, however the heaveist known white dwarf is only 1.35 solar masses. https://earthsky.org/space/smallest-most-massive-white-dwarf/
What's the cause of this difference in mass?
blademan9999
- 3,051
19
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3 answers
Paradox about white dwarfs and ionization
I am facing a dilemma. The fact that matter is ionized allows ions and electrons to be much closer together than they are in atoms (Bohr radius $a = 0.5 \cdot 10^{− 10} \mathrm{m}$), and the result is that some stars, including white dwarfs, have a…
M. A.
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19
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1 answer
Why don't electrons and protons in a white dwarf combine before the electrons become ultrarelativistic?
I wanted to get a rough picture of how white dwarfs and the Chandrasekhar limit work. I wound up with an argument nearly identical to this one on Wikipedia up through the non-relativistic white dwarf. That is, I estimated the energy in a degenerate…
Mark Eichenlaub
- 53,961
17
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1 answer
Can nuclear fusion alone account for the energy output from type 1a supernova?
Unlike other supernova, which can vary in their size, Type Ia supernova are all about the same size. This is due to the fact that they are caused when a white dwarf star gains enough mass from its binary companion to reach the Chandrasekhar limit…
0tyranny0poverty
- 1,086
10
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1 answer
Does the electron degeneracy pressure alone prevent the gravitational collapse in White dwarfs?
The electron degeneracy pressure (EDP) dominates in White dwarfs, where the electrons are compressed to very high densities. EDP is a purely quantum mechanical effect that arises due to Pauli's exclusion principle - the fact that no two fermions can…
Solidification
- 12,736
10
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3 answers
How to cut a stone on a White Dwarf?
I've heard that white dwarf stars are extremely dense and hard. So, if I had a piece of white dwarf matter, would it be possible to cut it (or otherwise) into a custom shape? How could one do that?
Robert
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10
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1 answer
What is the Chandrasekhar-Friedman-Schutz (CFS) instability, exactly?
I am confused as to what the Chandrasekhar-Friedman-Schutz (CFS) instability is, exactly.
It seems to refer to this paper by Chandrasekhar, but I do not think this paper covers the full instability. In the first part of the paper, Chandrasekhar…
user1379857
- 12,195
10
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1 answer
Why is the white-dwarf mass distribution highly peaked?
I am doing an undergraduate course in astrophysics. The lecturer mentions that observed white dwarfs have a mass distribution that peaks at around 0.6 solar masses. Consider the plot from…
thedoctar
- 526
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10
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1 answer
Does matter found at densities of white dwarfs "feel" more like a solid, liquid or gas?
I'm wondering what it would be like to touch or interact with very dense degenerate matter like this found at white dwarfs. I understand that white dwarfs are initially very hot, but for the sake of this question, let's assume that we can get close…
Abanob Ebrahim
- 3,974
9
votes
1 answer
Are there primordial populations of neutron stars and white dwarfs?
There is a well-known prediction that density fluctuations in the first moments of the Big Bang produced primordial black holes. Black holes from stellar collapse have their masses constrained by stellar dynamics, so stellar black holes are…
rob
- 96,301
8
votes
2 answers
What is the theoretical lower mass limit for a white dwarf?
This question in inspired by this other one, which asks what is the theoretical lower mass limit for a gravitationally stable neutron star (not the Chandrasekhar limit which is the upper mass limit for a white dwarf, or the effective lower mass…
Gro-Tsen
- 850
7
votes
1 answer
What's the transition from "metal" to "electron-degenerate matter" look like?
Question: Say that we had metallic water and compressed it until it qualitatively resembled the state of matter in a white dwarf: what would that transition look like?
Background (revised to be shorter)
In an answer, I claimed that, as water was…
Nat
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7
votes
1 answer
Gravitational binding energy of a white dwarf at Chandrasekhar limit?
I was trying to calculate the gravitational binding energy of a white dwarf just before it went on a type Ia supernova in order to calculate the kinetic energy of the ejecta, but I wasn't able to get the radius since the radius is zero at the…
Abanob Ebrahim
- 3,974
6
votes
2 answers
Why does a star beyond a certain mass limit (Chandrasekhar limit) only become a black hole?
Why does a star beyond a certain mass limit (Chandrasekhar limit) only become a black hole?
A star is first made of hydrogen, it undergoes nuclear fussion reaction combining hydrogen into helium and releasing a large amount of energy. This process…
user40647
- 125
6
votes
1 answer
How does fermion degeneracy affect elastic scattering in astrophysical compact objects?
As I currently understand it, absorption processes or inelastic scattering involving fermions in a degenerate gas are strongly inhibited, because to change the fermion energy (or create a new fermion) requires it to be placed in a vacant energy…
ProfRob
- 141,325