Questions tagged [white-dwarf]
Questions about electron degenerate stellar remnants.
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Why did Chandrasekhar use 2.5 for molecular weight in 1931?
I understand that the history of the Chandrasekhar limit is complicated (see, for example, Edmund C. Stoner and the Discovery of the Maximum Mass of White Dwarfs, Michael Nauenberg, JHA 39:297, 2008 / ...
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What is the maximum radius of a pure iron-56 planet?
Suppose we are building a pure iron-56 planet atom by atom, how large can it get in terms of radius before it collapses into a black hole?
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How does the Chandrasekhar limit relate to the ignition of carbon in white dwarf stars?
Why carbon in white dwarfs ignites (deflagrate, detonate) at the Chandrasekhar limit? The limit relates stability of the star made of degenerate electron Fermi gas to the white dwarf mass without a ...
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After a Type Ia supernova explosion, what becomes of the degenerate matter?
A white dwarf below 1.44 solar mass in a binary system may accrete mass from its companion. If its core reaches the temperature for carbon fusion during this process, the white dwarf may reignite in a ...
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How do I estimate the number of neutron stars and black holes relative to the number of stars in the main sequence and white dwarfs?
Recently, I had a homework question that gave me the mass of a main-sequence star, that is, M_tp = 0.9 M_solar, and the population formed at the same time. I am supposed to use the stellar birth ...
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Do “neutrino supernovae” exist?
Core collapse supernovae release most of their energy in the form of neutrinos. About 1% of the neutrinos are absorbed by the thick outer envelope which powers a spectacular supernova explosion.
Core ...
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What is the spectral reflection curve of cold white dwarfs and neutron stars?
Suppose that I got a white dwarf and a neutron star and after some trillions of years their temperature are down to just a few °K so cold that they don't emit any appreciable black body radiation.
Now,...
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Are white dwarfs made of carbon or electron degenerate matter?
I know that white dwarfs are composed primarily of carbon but are supported by electron degeneracy pressure. Is the electron degeneracy pressure produced by carbon atoms, or is the core of the white ...
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What determines the temperature of a white dwarf?
Can someone please explain what determines the temperature of the white dwarf? Is more massive white dwarf hotter ? Also, is the density of a white dwarf always a constant?
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The two channels of Type Ia SNe and their use as standard candles
As we know, Type Ia supernovae are used as standard candles since their absolute luminosities are expected to be roughly constant. The consensus model, as seen from the Wikipedia page, suggests this ...
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What would be the product between the collision of a white dwarf and a main sequence star?
Would this ever happen? If it would, what kind of star/supernova would this create? Does it depend on the mass of the main sequence star?
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Type Ia supernova by fallback?
Is it possible for a massive star of more than 1.4 solar masses (probably around 3 or more but below the threshold for type II) to collapse into a white dwarf and a planetary nebula, then go supernova ...
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Hypothetical upper and lower bounds for Chandrasekhar limit based on composition?
Disclaimer: I'm going to be using the term "white dwarf" to refer to any spherical celestial body made of electron degenerate matter. If I had a better term, I would use it.
The ...
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Do gamma rays escape from stars when turning into white dwarfs
I'm very curious about this : if the Sun were to become a white dwarf, would Earth get blasted with high-energy electromagnetic radiation? I know that current predictions say that Earth will be ...
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Do all C-O white dwarfs have more-or-less the same proportions of carbon and oxygen?
Type 1a supernovae are known for having very consistent energy yields, and they are caused when a carbon-oxygen white dwarf reaches the Chandrasekhar limit of about 1.4 solar masses. Since type 1a ...
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What does an electron-capture supernova leave behind? A white dwarf, a neutron star or nothing?
Somehow, none of the many articles I've read about the recent discovery of electron-capture supernovae has specifically said what they leave behind as remnants.....
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Is something wrong with my luminosity calculation?
A few million years after a white dwarf forms, its surface temperature reaches $100000\text{K}$, while its radius is $0.01R_\odot$. Would this mean that its luminosity is $\Big(\dfrac{100000}{5778}\...
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Uranium accumulating inside a White Dwarf?
A couple of days ago, there was news that "Some dead stars may harbor enough uranium to set off a thermonuclear bomb", which is basically a teaser for Actinide crystallization and fission ...
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Can mass loss via accretion occur on stellar remnants?
We know that normal stars can lose mass to a binary companion. But can this happen to neutron stars and white dwarfs? Let's say a stellar black hole is being orbited by a white dwarf or neutron star. ...
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What would happen if a neutron star merged with a white dwarf?
We've heard of neutron star mergers and white dwarf mergers. But what would result in a neutron star merging with a white dwarf? Would there be a similar super/kilonova, are there any examples of it, ...
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Would dropping a white dwarf or a "still-hot" stellar core into a large planet or brown dwarf create a star?
In the Wikipedia article about stellar engineering, I found this quote:
In The Saga of the Seven Suns, by Kevin J. Anderson, humans are able to convert gas giant planets into stars through the use of ...
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Exactly how long does it take for the exposed core of a star to cool from its starting temperature (several billion K) to ~50,000 K?
OK, I didn't know how I should word this question. But the basic point is that most white dwarfs that we have classified fall in temperature ranges from ~50,000 K to 6000 K. However, at the end of a ...
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What is the coolest white dwarf known?
Okay, so in this ArXiv report from 2014, scientists discovered the coolest white dwarf, with a temperature of below 3000 K. However, as this report was from over 6 years ago, I think this information ...
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How long does it take for a white dwarf to undergo a type Ia supernova?
I read about white dwarfs and their relation to Type Ia supernovae, and I want to know how much time passes between when the white dwarf passes the Chandrasekhar limit and when the white dwarf ...
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Do more massive stars become larger or smaller white dwarfs?
I wonder whether e.g. stars more massive than the Sun (but below the mass where they'd go supernova) would become larger or smaller white dwarfs than a white dwarf Sun. Since Procyon B is larger than ...
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Assuming proton decay is false, what's the ultimate fate of a neutron star or white dwarf?
A still unproven theory that protons can decay, and have a halflife of $10^{30}$ years or so, meaning eventually all matter will dissolve because their constituent protons and therefore neutrons will ...
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How can planet (WD 1856b) revolve around its smaller mass WD 1856?
WD 1856 has smaller mass than WD 1856b. So how WD1856 making
WD 1856b revolve in the orbit? Its clear violating space-time curvature.
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What's the big deal with WD 1856+534 b?
A few days ago (september 2020) a planet candidate was announced orbiting white dwarf WD 1856+534. Some media outlets announce it as the First Possible ‘Survivor’ Planet around a white dwarf, while ...
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If Sunlike stars become a red giant and eventually a white dwarf, what do red dwarfs become?
The Sun is said to become a red giant at the end of its life (before that it will become an orange subgiant first and then an orange giant or so) and after ejecting its outer layers it should become a ...
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Is the object a pulsar
We have a star having 1.8 solar mass. Justify any four means (measurable/ observed properties) by which you can identify that the object is a Pulsar and not a white dwarf or a Black Hole.
So one ...
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What is considered "contact" for contact binary white dwarfs, and roughly how long can they stay that way before merging?
The question Why do they think that WDJ0551+4135 is “snowman shaped” i.e. a contact binary? has also raised the question of what a contact binary is or isn't, and how hard it might be to see one if it ...
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Can white dwarfs have accretion discs too?
Neutron stars and black holes can have discs of accreted matter for they have an extremely high gravitational pull. While white dwarfs don't have such high gravity theirs is of course also extremely ...
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The colour of blue dwarf stars
The paper "M dwarfs: planet formation and long term evolution" describes blue dwarf stars, a hypothetical next-stage in the lifespan of red dwarf stars within a certain mass range, after which they ...
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Could an Applegate-like mechanism operate in AM CVn systems?
One of the controversies surrounding the detection of exoplanets around post-common envelope binaries is the possibility that the orbital period variations observed might be the result of the ...
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Higgs Field inside a White Dwarf
White dwarfs rank among the hottest things in the universe.In the early years of the life of the universe ,universe was very hot and the Higgs field was deactivated causing all the particles generated ...
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Why would tidal forces on planets become more intense when a star becomes a white dwarf?
I was puzzled by this press release by the Royal Astronomical Society: "Small, hardy planets most likely to survive death of their stars" - phys.org, May 14, 2019
Astrophysicists from the Warwick ...
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Do white dwarfs produce stellar wind? If not, why is that?
I've been told white dwarfs don't produce stellar wind like the sun produces solar winds. I don't quite understand why that is and can't really find any evidence that confirms or denies that.
My ...
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Do white dwarfs lose mass as they fade to black dwarfs? Is there a correlation between temperature, mass, and radius?
I'm having a difficult time understanding certain behaviors of white dwarfs.
I understand how mass is lost in the red giant to white dwarf transition process. I understand that white dwarfs can ...
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Have any more "white dwarf pulsars" been discovered or searched for?
Back in 2016, Marsh et al. reported that the binary system AR Scorpii exhibits complex radio signals similar to those observed from traditional pulsars. In particular, pulsed synchrotron emission ...
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Are white dwarfs the ones always absorbing mass from a companion?
It seems to me every time I see stellar remnant binary systems where there is a white dwarf and another star or something, it appears that the white dwarf always pulls mass from the star.
What if the ...
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White Dwarf/Degenerate Gas Behaviour
just want to try to clarify a few things about the nature of White Dwarfs and degenerate gases.
So if a white dwarf is help up by an electron degenerate gas, the electrons are unable to lose energy ...
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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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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 supported mainly by electron degeneracy pressure and that if it gains more than about 1.4 solar masses from any source (such as a companion star or a collision), it ...
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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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