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Questions tagged [white-dwarf]

Questions about electron degenerate stellar remnants.

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Is the structure of crystalized white dwarf related to nuclear pasta?

There is news of an analysis of a large number of nearby white dwarfs revealing a "pile-up" at a certain point in their cooling which has been predicted to happen due to a phase change where nuclear ...
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How long does it take for a white dwarf to cool to a black dwarf?

I was reading on white dwarfs, and I came across this sentence— Without energy sources, the white dwarf cools to a black dwarf in a few billion years.[1] However, when I looked into the Wikipedia ...
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Which Chandrasekhar Limit do I use? 1.39 or 1.44?

Different sources online say that the Chandrasekhar Limit is either 1.40 or 1.39, or 1.44 solar masses. Why the discrepancy? I heard it might have to do with the composition of the white dwarf, but, ...
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Can life on earth be supported by only a Red Dwarf star or a White Dwarf(state still hot not cooled enough yet)?(Provided it is near to the star)

Can a red dwarf star or a white dwarf have enough energy to support life on earth? How it will change the climate and the seasons of earth if it is our only star? (energy source)(Expecting it to ...
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Gaia Gbp - Grp: why does it get larger as star gets redder?

As an enthusiastic amateur scientist, I'm plowing my way through a cool Gaia DR2-based paper, "An Empirical Measurement of the Initial-Final Mass Relation with Gaia White Dwarfs". I'm doing all right, ...
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3answers
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Is there a possibility that a white dwarf can turn into a neutron star or a black hole?

I know that a white dwarf is mainly balanced by electron degeneracy pressure and that if it gains more than 1.4 solar masses from any source (such as a companion star or a collision), it explodes as a ...
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If two white dwarfs collided, would they become a star?

Would the temperatures during such a collision be able to ignite nuclear fusion, bringing the dead star back to life? If so, would it only be able to fuse for a short time before running out of fuel, ...
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Would the heliosphere disappears if our sun becomes a white dwarf?

Just curious I like to know if one fine day our Sun turns into a white dwarf at the later stage of its life, would the magnetic bubble, heliosphere gets thinner and eventually disappear? also at this ...
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How does a planet lose mass to its host star?

How do bodies like WASP-12b lose mass to its central body? The process is never really explained in popular media, instead showing visualisations of a thin veil of gas being "sucked" in a rather ...
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What happens if a white dwarf collides with a star like our sun or a red dwarf?

Would it explode in a supernova or will it form a new star?
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Question about number density of electrons

I somewhere see that in a white dwarf, we have this equation: $\rho = 2 N_e * m_p / V = 2 n_e * m_p$ where $N_e$ is the number of particles (in this case e, electrons) and $n_e$ is the number ...
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What if a white dwarf is less massive than her partner?

For example: a system with a 0.2 solar mass white dwarf orbiting a 0.25 solar mass red dwarf. Does the red dwarf steals mass from the white dwarf or vice versa.
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What is the condition for the number density of a gas to be ultra-relativistic or non-relativistic and degenerate or ideal

What is the condition for the number density ($n$) of a gas to be ultra-relativistic or non-relativistic and degenerate or ideal? I found problems in this subject when I was reading about White-...
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What is a cold white dwarf?

Is a cold (3800K, or so) white dwarf still be considered/in degenerate state. Or, how can a gas be degenerate and cold?
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What does a black dwarf look like?

A black dwarf is a hypothetical object that is the end result of the cooling of a white dwarf. None yet exist, because there hasn't been enough time in the age of the universe for them to cool down ...
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Which would be safer: removing hydrogen or adding hydrogen to our sun?

If we want to extend the lifespan of our habitable zone safely, would it be safer to institute a yearly 'tax' on our suns outer layer of hydrogen, or a yearly 'subsidy' to our suns outer layer of ...
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Origin of terms “white dwarfs” and “red giants”?

Can someone explain my why "white dwarfs" and "red giants" were so named? And maybe that's a silly question but why not in the opposite way? @EDIT Is this somehow co-related with Stefan–Boltzmann law?...
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What is “superficial gravity”

I have seen the term superficial gravity used and it seems to be equivalent to surface gravity seen, e.g., here http://arxiv.org/pdf/1701.02295 Is there any difference between superficial and ...
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White Dwarf and Degenerate Matter

How do we know degenerate matter exists on white dwarfs? Is it purely hypothetical or have we observed it before? Have we ever created a form of degenerate matter on earth?
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Will Sirius B start accreting from A and become a supernova type Ia?

Sirius B is a massive white dwarf of 1 Solar mass, orbiting at about 25 AU distance from the 2 Solar mass Sirius A. As it evolves and expands, will the A star start shedding matter to the white dwarf, ...
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white-dwarf merge in binaries

Two white dwarfs with a total mass $>1.4\:M_{\odot}$ merge. It may trigger a type Ia SN explosion. How about the three cases below? Two low mass WDs merge, total mass $<1.4\:M_{\odot}$. A low ...
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Is the lower mass limit of a neutron star the same as the upper mass limit of a white dwarf?

If not, when can a white dwarf be more massive than a neutron star?
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What is the most distant observable White Dwarf known?

I attended a talk last week about Type 1a supernovae with the focus being on double-degenerate systems as potential progenitors for them. We were shown a graph of White Dwarf (WD) mass distribution ...
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Are white dwarf stars supported by proton degeneracy as well?

In general, fermions form a degenerate gas under high density or extremely low temperature. It's clear that white dwarf stars are supported by electron degeneracy pressure. However, there are still a ...
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How can white dwarf form Oxygen ? (Temperature problem)

I’ve got a question about white dwarfs and oxygen. I read in a book that a temperature of 100 million degrees is required to fuse Helium in the core of a red giant. The Helium fuses into Carbon by ...
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Cosmic events as standard candles

Type 1a supernovae are used as standard candles. Are there other high energy cosmic events which can be used as standard candles. For example, collapse of neutron star into a black hole is also ...
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Are there radio white dwarfs?

We have discovered about 2500 radio pulsars. Part of them show pulsations in other bands like X-ray and gamma ray. The radiation mechanism remains unclear now. I wonder whether there are radio ...
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Chemical reactions in white dwarf and carbon allotropes

White dwarfs consists mostly of carbon and oxygen. In my opinion, they are too hot to contain these elements in molecular form and hence chemical reactions does not happen (I think resulting CO2 will ...
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Why does the Chandrasekhar limit affect white dwarfs differently?

The Chandrasekhar limit is the maximum mass of a stable white dwarf star. Beyond this, a carbon-oxygen white dwarf will typically explode in a type 1a supernova, due to the nuclear reactions at those ...
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If a white dwarf collides with a giant star, could it create a TZO?

Thorne–Żytkow objects (TZOs) form from collisions between neutron stars and main sequence or giant stars. Ultimately, the neutron star becomes the "core" of the giant star. However, could this also ...
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How can a low-mass star increase its mass to 1.4 Msun? [closed]

In my astronomy class I learned that a only low-mass stars (< 0.5 Msun) will contract, and then become degenerate, until it is a white dwarf. However, we also learned about the Chandrasekhar limit, ...
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Can life survive on the equator of cooled and fast rotating white dwarf or neutron star?

As I know, some stars produces carbon, nitrogen and oxygen when they are old and become white dwarfs or neutron stars. And even their surface gravity is strong, it may rotate very fast so that the ...
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What is the difference between a neutron star and a white dwarf?

What is the difference between a neutron star and a white dwarf? I know that both are very dense even if they go through different phases.
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How is the first detonation in Supernove type Ia triggered?

Ok, I read about the Supernova of type Ia and I found out that there are two detonations happening. First one is in helium shell around the white dwarf and second one seems to be triggered by the ...
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How bright can white dwarf stars glow as they accrue matter?

I realize this is kind of general as it would depend on the size of the white dwarf and the rate of accrual. The general idea I got thinking about is what would happen if a white dwarf star - lets ...
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White dwarf's impact on orbiting bodies

Recently the Kepler telescope in its study of white dwarfs detected the first planetary object transiting a white dwarf in the data from the K2 mission. It was consistent with earlier theories' ...
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How much mass will the Sun have when it becomes a white dwarf?

In 4 billion years, when our Sun sheds all of its outer gas layers and turns into a white dwarf, how much mass will the white dwarf have compared to what the sun has today? Will the planets still ...