Questions tagged [white-dwarf]
Questions about electron degenerate stellar remnants.
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Is Kepler's Supernova a double degenerate or single degenerate supernova?
I know that SN 1604 is a Type Ia supernova. But was it formed from two white dwarfs colliding in a double degenerate scenario, or in a single white dwarf accreting matter? I have seen supporters of ...
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Do neutrinos account for approximately 99% of the energy released by Type 1a supernovae as they do for Type II 'Core collapse' supernovae?
So many accounts say that neutrinos carry away about 99 percent of the energy from a 'traditional' supernova (giant star at end of its life), but what about a white dwarf detonated after accretion?
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Required temperature for a nova
On the wikipedia page of the nova is said that the CNO cyle, which converts hydrogen into helium, starts on the surface of the white dwarf when the temperature reaches about 20 million K.
My question ...
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White dwarf supernova luminosity
I understand that the mass limit for a white dwarf is 1.4 solar masses, and therefore approaching it would cause a white dwarf (type Ia) supernova, and thus it is a standard candle. I understand this ...
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Why does a white dwarf sometimes go 'nova' and sometimes supernova (type 1a)?
Obviously, when a white dwarf goes truly supernova, there is nothing left, not even, I have heard, a neutron star or black hole...
But when certain white dwarf stars accrete certain amounts or types ...
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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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Where will all atoms on the Earth end up when the Sun engulfs the earth?
I am curious about what will happen to all atoms on the Earth including all of our atoms after the Sun engulfs the Earth?
Will they become the part of the Sun's white dwarf?
Or most of them will be ...
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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 ...
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What are the most up to date, accepted, evolution stages of big stars that end in compact objects or a planetary nebula?
There are numerous charts and diagrams showing the stages of stellar evolution, as:
or
among many more (you can find several after googling a little), for example.
When I studied my B.Sc. on Physics,...
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How to calculate the number density of electrons?
I am trying to calculate the number density of electrons (number of electrons/m^3) for a white dwarf, knowing these parameters :
the mass and radius of the white dwarf (therefore its density (kg/m^3))...
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Question about a White Dwarf formula
I have a question regarding the White Dwarf radius formula given on wikipedia, in terms of what units I am supposed to use and what expected values of one variable would be.
https://en.wikipedia.org/...
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Why would rocky earth-like planets be rare around white dwarf stars?
I came upon an article here https://phys.org/news/2023-11-white-dwarfs-life-planets.html
The author thinks that rocky earth-like planets could be rare around white dwarfs.What could be the reason for ...
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Why do white dwarfs cool down so slowly?
I read that when white dwarfs do not proceed with nuclear fusion, the heat radiation from it is solely based on heat it retained in the past
But then, it floats in an almost 0 K empty space. So, why ...
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Degenerate object accretion - what happens after it becomes a PMO?
Degenerate objects such as neutron stars and white dwarfs can be accreted from by other objects. As the degenerate object loses mass, it could pass through different mass ranges which govern the ...
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Proportion of oxygen in a typical white dwarf
What's the proportion of oxygen in a typical white dwarf relative to the proportion of Carbon?
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What crystal structures are predicted for the crystalline phase of matter inside crystalizing white dwarfs? Does it depend on the carbon/oxygen ratio?
The abstract of Venner et al. (2023) A Crystallizing White Dwarf in a Sirius-Like Quadruple System includes the following:
The location of HD 190412 C on the 𝑇eff − mass diagram implies it is ...
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How small stars help with planet formation
As I understood, low mass stars in their core go through fusion, but only the fusion of hydrogen happens. When it depletes hydrogen, fusion stops as temperature is still not high enough to support ...
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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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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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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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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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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 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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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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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 ...
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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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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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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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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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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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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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How do stellar temperatures vary?
The temperature of the surface of the Sun (photosphere) is between 4500° - 6000° Kelvin. Inside the core, it's around 15.7 million degrees Kelvin.
In other types of stars (neutron stars, white ...
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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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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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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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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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