White dwarf Definition and 62 Threads

It’s my understanding that a nova happens when you have a close binary star, and one component is a white dwarf. The white dwarf sucks hydrogen from its companion, the hydrogen piles up on the surface of the dwarf until it’s hot and dense enough to undergo nuclear fusion. Ka-boom. Right? Why is...

Yes, I understand that once white dwarfs get cold enough, they aren't luminous enough to get observed, so my question could be interpreted as "when did the earliest white dwarf evolve, and how cold is it now"? This is the article that motivated this question...

An article came up on Phys.org about a white dwarf drawing in material from the planetary system surrounding it. Is this the ultimate fate of our solar system? https://phys.org/news/2022-06-dead-star-cannibalism-planetary-far-reaching.html...

As this page says: "A burnt-out star is basically a gas of electrons and ions. " In white dwarf, further collapse of the star is stopped by electron degeneracy pressure. But, if the star material is just a soup of ions and almost free electrons, why don't the electrons and ions separate into...

This is part of the text from the link: I want to ask several things: 1. From the second paragraph: "As soon as the sun begins to burn more hydrogen, it would be considered a “red giant”. " But from first paragraph: "But when the star has nothing left in the core to burn, gravitational...

Some estimates through calculating the sun mass loss and increase in mass loss say that the white dwarf phase of the Sun will have roughly about 50% the current mass of the Sun (not sure about it). Whatever the actual mass loss is going to be, assuming that the 50% mass loss is true, where would...

How did you find PF?: duckduckGo search. My math is very weak and I don't like explanations done using math. I read books with very little math. I try to use reason based on what I've read. My understanding is time slows down in gravity and it will actually stop at the event horizon (see...

I read this interesting article today, the original paper here. Abstract:

Hi! I have read a calculation about a white dwarf star assuming the electrons are both ultra-relativistic and degenerate. My questions is - how come the ultra-relativistic assumption doesn't contradict the "degeneracy" assumption. Degenerate means the electrons are filling out all the lowest...

So far, I am provided with all the required values for calculation, except N. If N = total number of electrons in star, then using N = mass of star/ mass of an electron should be no problem. Am I right?

How is neutron degeneracy pressure able to support a much higher density object such as a neutron star where electron degeneracy pressure only supports a comparatively less dense object such as a white dwarf. Conceptually I would think electron degeneracy pressure to be stronger due to the...

Is it possible for white dwarf star in binary system where it is feeding off its partner star to collapse directly into a neutron star? Or is something inherent in the formation of neutron stars where they must be formed from supernova?

I try to get a correct result for the radius of a standard white dwark (roughly 10000 km). I just want the order of magnitude , i.e with the common values of a solar mass into Earth radius sphere. From http://www.astro.umontreal.ca/~bergeron/CoolingModels/Synthetic_Calibration.pdf page 1223...

I just finished watching the video "The Last Light Before Eternal Darkness – White Dwarfs & Black Dwarfs" At 5:17 he mentioned quantum tunneling will take up a timespan so long that calling it forever is ok. But nothing takes forever,so,how long will it actually take? ps:I later realized...

Hello everyone. I am trying to solve a problem whose statement reads as follows: Neutron stars have radii of ##\sim 10## km. If we assume that before the collapse the nucleus of the white dwarf precursor has a mass equal to that of Chandrasekhar, estimate the energy generated in the collapse...

Homework Statement The sun has a rotational period of 25 days. Finding the rotational period if it can shrink to form a white dwarf (##R_{WD}=10^3Km##). Knowing that the density of magnetic flux of the Sun on the surface is ##1 Gauss##, finding the magnetic flux of the white dwarf. Homework...

For the last 88 years we have used Subrahmanyan Chandrasekhar's calculations to determine the maximum mass of a white dwarf. As a result of that calculated mass limit, a peak brightness was derived and the Standard Candle was born. However, those calculations were made based upon certain...

Homework Statement I have a problem with question (b), in what follows there's a quote of the problem and its solution. (again from Bergersen's and Plischke's textbook). Homework EquationsThe Attempt at a Solution [/B] My problem is with the last expression in (d) I get 54 instead of 36. To...

Homework Statement Calculate the radius of a 1.3 Msun white dwarf using the mass-radius relation for white dwarfs. Give the answer in solar radius. Homework Equations Mass-radius relation: $$R \propto M^{-\frac{1}{3}}$$ The Attempt at a Solution So I've tried the following: $$R_{D} \propto...

Hi, My textbook has a multiple choice question about which stellar object has the highest surface temperature and the answer was a white dwarf. However, one of the options was a neutron star. Neutron stars are much denser and have been crushed by gravity even more plus they are rotating at...

Hello guys. I'm working to compute de max. mass for a white dwarf through solving the hidrostatic equilibrium equations. ( The classical ones, not TOV), and using an EoS made by my own, that considers the Fermi Pressure and stuff. When i use the EoS for a carbon white dwarf ( i do get the...

Hello, I read at a couple of places about white dwarfs having a spectrum similar to that of the sun. What does that mean or associate to? Thanks in advance.

I'm curious. I want to model it to understand stellar evolution better. Does anyone know what the most massive single white dwarf is?

I think this could be a good chance that we see how neutron stars form from White Dwarf mergers. The combined mass of the two are less that than required for a type Ia Supernovae. Won't they merge and collapse into a neutron star? What does everyone else think might happen. I want to be sure if...

Hello, I was just brainstorming for futuristic inventions with context for a sci-fi, high fidelity game (because I'm too cool to revise for exams) - and I thought of one, but my physics and engineering knowledge is at best sketchy when it comes to gravity and nuclear fusion combinations, I was...

Note that the code I am using is Python. Currently, I am attempting to numerically solve the equations of state that give rise to the Chandrasekar limit for a white dwarf star. My code works for a simple harmonic oscillator given the correct equations of motion, but does not compute the correct...

Hello, I will need to talk to students about the evolution of a solar-like star. We will look at a diagram like the following: It will be a descriptive presentation, no mathematics. I know pretty well what happens until the formation of the carbon core. The linear upper line happens because...

The mass-radius relationship for a white dwarf star is defined by : R= (9pi)^0.66 /8 * h^2/m1 * 1/(Gm2^1.66*M^.333), where m1= electron mass, m2=proton mass, G=grav. constant, h=planck's constant I want to take a proportion with the solar mass and solar radius, which would involve a division...

A normal star's core consists of Hydrogen but a white dwarf is itself the core and it consists of stellar ash. So the degeneracy pressure is exerted when this stellar ash becomes very dense (In other words when the white dwarf becomes very dense). Am I right? The density of a white dwarf is so...

Hi fellas, I have taken white dwarf stars as my undergrad thesis choice, so I need some suggestion on good books on dwarf. please suggest me books for both reading and for some mathematical derivations regarding the white dwarf

hi guys, I wonder if I have fully understood the Fermi Dirac statistics properly, but I have a question on it regarding its application in the white dwarf research. I read the Fermi energy is applicable for T=0, now if the core of a white dwarf is too hot then how can we apply the Fermi Dirac...

dear friends, can I get a link to the original paper by Chandrashekhar where he derived the limit for white dwarf? also you can suggest me other good papers deriving the limit. regards

The question is attached. I'm not sure how to approach to part (b). The energy released could be in 3 forms, the rest mass energy for those matter ejected during supernova explosion, the binding energy released as the atomic structure changed, the ejected matter carries off some kinetic...

Apparently this binary system is providing yet further confirmation of GR. It is only the second NS with a precisely determined mass ~ 2 solar masses. Pulsar-White Dwarf Pair Proves Einstein’s Theory of Relativity http://www.sci-news.com/astronomy/article01046.html...

Homework Statement Calculate the kinetic energy generated when a white dwarf in a binary system accretes enough material to increase its mass beyond the Chandrasekhar limit (1.4 solar masses) and collapse to the radius of a neutron star. radius of white dwarf- 5520 km radius of neutron...

My advanced statistical mechanics professor claimed that there were very few doctorate-granting schools in North America doing research in white dwarves. While that professor might have some fame as far as white dwarf research is concerned (along with Winget, that professor is one of the biggest...

instead of typing it out, here is the problem I know what to do, my math just isn't good enough to combine the equations properly. Been at it a few hours, brain hurts, please help!

Hello! Homework Statement The question is "Calculate the energy released if a 1 solar mass white dwarf undergoes a thermonuclear runaway and converts 0.5 solar mass of carbon (A=12) to iron (A=56)." I've only ever done nuclear equations with hydrogen fusion, with four hydrogens to one...

Homework Statement Compute the numerical constant C for an electron gas (take Z = 6 and A = 12) and determine the radius of a white dwarf whose mass is 0.6 solar masses. h\ =\ 6.62606876(52)\ \times\ 10^{-34}\ Jh\ =\ 6.62606876(52)\ \times\ 10^{-34}\ J\ s\ s m_{e}\ =\ 9.10938188(72)\...

What a wonderful coincidence to find such an old star so close by! http://phys.org/news/2012-04-astronomers-billion-year-old-white-dwarf-stars.html Respectfully submitted, Steve

Homework Statement An apple is dropped from a height of 12.8*10^6 m above the surface of the white dwarf. With what speed does the apple strike the surface of the white dwarf? M of white dwarf= 1.99*10^30 gravity of white dwarf= 3.29*10^6 Homework Equations Vf^2=Vi^2+2a(deltaX)...

Neutron stars are held together by extremely strong gravitational force. What would happen to a chunk of the star if it had been removed and left to stand alone? Same question for a chunk of a white dwarf?

Hi all, If we develop the right kind of space ships, would it be possible to do non-human robotic missions to a white dwarf? What would it be like?

Homework Statement This is a past exam question that I am trying to get my head around but keep getting stuck Show that if a white dwarf were at the centre of the solar system instead of the sun, it would have an apparent visual brightness of -18.6mag. Assume that the white dwarf has surface...

Just pondering Eric Agol's recent paper on White Dwarf habitable zones and the pace of cooling of white dwarfs (WDs.) He uses models of Carbon core WDs with helium atmospheres, but I am wondering if pure helium WDs would last three times longer. Opacity from the atmosphere slows down heat loss...

I know that nuclear fusion is the source of energy for our sun and most of the other stars. Neutron stars and white dwarfs have very high surface temperatures. What is the source of their energy?

Homework Statement Use a coupled fourth order Runge-Kutta, to find the structure of white dwarf stars. I think I am applying the Runge-kutta method wrong? Variables defined in C code notes Homework Equations Equations in c code. and in attached images. The Attempt at a Solution This is...

We have the rate of change of number of electrons with energy directly proportional to the volume in an 3-D potential well. For a white dwarf, the mass is inversely proportional to its volume. If we consider the electrons in a white dwarf to be in such a potential well, dN/dE becomes...

hi i want to ask aquestion what is the biggest qatar: black hole or white dwarf or nutron star or the sun please i want to know the biggest one and then and then and the smallest one thaaaank you very much

So after a long time I finally figured out how the white Dwarf classification system works. Basically its first the letter D Followed by a temperature Correct me if I am wrong but, DO, DB, DC, DZ white dwarfs are associated with a specific effective temperature of the star. However...