That's a question I've been asking for a while is "how exactly do white dwarves explode?". Thanks to the slides and your explanation, I now know something I've been wondering for at least a decade :)
Even you simplify that stars stop at Iron, when the actually stop at two Silicon-28 combining to Nickel-56. Then it is the decay back to Iron-56 that keeps the supernova bright.
Always thought I wasn't smart enough for all this in spite of a BS Chemistry from CSUN in 1979. Now I'm 71, suffered my first concussion five years ago and with these lectures, I'm finally understanding at least the basics of cosmology. By the way from about 69-73 I catalogued about 30 of the Messier objects with a 3 inch refractor as a teenager.
Take a generic white dwarf in a one star system. For example, our solar system in a few billion years. Over trillions and trillions of years it will simply cool down... but is something else going on? This white dwarf is drifting through space... and there's dust and gas in space. It's going to snag some of it and get a little bit more massive. Will it ever get massive enough to blow up? Say.. in 50 or 100 trillion years?
I'd imagine it depends on where it is and what's going on around it. There'd probably be some of that going on but eventually the gas would get too scarce to cause novae anymore. Pretty cool thought though!!
I asked Fraser Cain Sunday night to explain why some white dwarfs in binary systems produce Nova and others produce Type 1A Supernova. Then I thought, I'll bet Jason Kendall has a comprehensive video explaining this. I was right!!!😂
How is it that white dwarfs are able to accrete as much material as needed to explode as a Ia supernova without first expelling that material in successive dwarf novae events?
The progenitors of type 1a are polar (highly magnetic) white dwarfs. The mass stolen from a companion star is sucked in at the polar regions. It accumulates INSIDE the stellar corpse. Like a giant pressure cooker, they all have the same breaking point, the same interior capacity (230 million Gauss). The chandrasekhar limit is the net minimum mass of a pulsar. It has nothing to do with the explosion.
The progenitors of type 1A are polar white dwarfs (like AN Ursae Majoris B.) The chandrasekhar limit has nothing to do with why the explode. 1.44 S.U. is merely the minimum net weight required to form a pulsar. 🤠✌️
Doc: many limits are at play for our earth's elemental abundance. It does have to do with the chandrasekar limit in white dwarfs. In white dwarfs it is the electron degeneracy pressure, but in neutron stars it is the oppenheimer volkof limit due to neutron neutron or nuclear stiffness not electron speed operating. The quarks will reach the limit of being freed at high enough pressure, to form a quark soup. This quark soup can in no way be simulated at this time, but soon maybe. The mass of this limit of nuclear stiffness is between 2.14 & 2.17 solar masses limiting not due to theoretical theory but direct observation. We do not have the maths or theory for this oppenheimer limit exactly at this time. Also it is thought that spin angular momentum can hold this up to make the exact number unknown.
I'm going a bit crazy here. The slide (15:08) says "as the density rises the temperature does not increase" in reference to white dwarfs is that a mistake? Did you mean to say the pressure does not increase? I thought this whole thing was about how the temperature increases to a point that it starts to ignite carbon oxygen burning. If the temp doesn't increase how does it reach a new ignition point?
For white dwarfs, at their high density, a new gas law takes over: • Pack many electrons into a tiny volume • These electrons fill all low-energy states • Only high-energy (high-pressure) states left Result is a “Degenerate Gas”: • Pressure is independent of Temperature. • Compression does not lead to heating. This means that the objects could, in principle, be very cold but still have enough pressure to maintain a state of Hydrostatic Equilibrium. During this time, while the electrons are degenerate, the nuclei are still "classical", so they can get hotter until their interaction with the degenerate electrons has enough energy to "lift the degeneracy" and change the state back to a more classical regime. That's the reason for the "helium flash" in AGB stars. Watch my video about the evolution of solar-mass stars. I talk about this in greater detail.
Hey dude, do white dwarfs produce magnetic fields that can be detected by the technology that we have now? I am so darn curious about the correlation between magnetic fields and the rest of matter, because it seems to be from my point of view and observations that magnetism is just as important. Static electricity creates magnetism, right? I'm not trying to be a troll I'm just bored and I love astronomy
Two responses: One, there is no effect of the universe's expansion on the size scale of the solar system. It's MUCH smaller than a Megaparsec. But, the recession of the Moon from the Earth is measured, and is the effect of the equiparatitioning of energy due to the actions of the tides. As the Earth's rotation slows to meet the month, and the month's length shortens to meet the day, the Moon drifts outward to balance out the orbital energy.
There is now evidence that there are several classes of Type Ia supernovae one type the single degenerate class happens as you described by mass transfer back and forth as a binary pair ages until a white dwarf reaches the Chandrasekhar limit are also able to form by the merging of two white dwarfs that exceed Chandrasekhar limit. The latter type of type Ia supernovae adds a complication to using type Ia supernovae as white dwarf mergers can actually exceed 1.44 solar masses depending on the mass of the two white dwarfs. They have resolved this issue by determining methods to tell the two types of type Ia apart but it shows how much more complex the situation has gotten. Two further weird oddities are type Iax where the star accretes helium which can result in a weaker explosion that may potentially be weak enough that some part of the star can survive. arxiv.org/pdf/1901.05461.pdf Another really weird white dwarf system is the until recently theoretical super-Chandrasekhar mass carbon-oxygen white dwarf where two massive white dwarfs merge together with a resulting mass sufficient to hold together and avoid collapse due to the ignition of carbon fusion in its interior. Earlier this year a team of Russian astronomers published in Nature that using Gaia parallax measurements we able to identify the WO type "Wolf Raynet star" WS35 is 3.07 kpc away and is most likely one of these stars that will eventually undergo a core collapse type Ic supernovae and likely a neutron star remnant. arxiv.org/abs/1904.00012
I like to think I have a fairly decent grasp of this material, but I keep questioning one main thing. When we talk about inflation and the acceleration of the universe, it always goes back to charts showing that the further away we look (aka the further back in time we look) the faster the universe is expanding. I guess I am just not grasping this simple concept, because I would expect to see galaxies further away moving away faster due to the fact that those images are further back in time. I would expect to see faster movement closer to the beginning of an "explosion" than (further away / earlier in time, in relative terms) than I do looking at objects closer. Am I just missing that the time adjustment for distance is compensated for in these diagrams? Because if not, then this is what I would expect to see in an explosion that is slowing down currently.
@@JasonKendallAstronomer Fair enough and certainly a true statement. But that still does not clarify my confusion. If expansion was slowing, then I would expect that as I look at galaxies further away (aka, further back in time), I would expect to see them moving faster than the galaxies that are closer or more recent in time.
@@3DMatterMakers yes and that is what those Nobel prize recipients expected to see as well...they were as surprised as anyone when they found that the galaxies weren't moving away as fast as they had thought...
Thank you... Now i know how novas can repeat more than once.
That's a question I've been asking for a while is "how exactly do white dwarves explode?". Thanks to the slides and your explanation, I now know something I've been wondering for at least a decade :)
The beautiful physics of the stars without equations! Wow!
Even you simplify that stars stop at Iron, when the actually stop at two Silicon-28 combining to Nickel-56. Then it is the decay back to Iron-56 that keeps the supernova bright.
Thank you for the nice lecture. Very informative.
So nice of you
Always thought I wasn't smart enough for all this in spite of a BS Chemistry from CSUN in 1979. Now I'm 71, suffered my first concussion five years ago and with these lectures, I'm finally understanding at least the basics of cosmology. By the way from about 69-73 I catalogued about 30 of the Messier objects with a 3 inch refractor as a teenager.
So, the lesson seems to be to learn Cosmology, one needs to be extremely clumsy with a ball-peen hammer?
Take a generic white dwarf in a one star system. For example, our solar system in a few billion years. Over trillions and trillions of years it will simply cool down... but is something else going on? This white dwarf is drifting through space... and there's dust and gas in space. It's going to snag some of it and get a little bit more massive. Will it ever get massive enough to blow up? Say.. in 50 or 100 trillion years?
I'd imagine it depends on where it is and what's going on around it. There'd probably be some of that going on but eventually the gas would get too scarce to cause novae anymore. Pretty cool thought though!!
jason, my standard kendle.
I asked Fraser Cain Sunday night to explain why some white dwarfs in binary systems produce Nova and others produce Type 1A Supernova. Then I thought, I'll bet Jason Kendall has a comprehensive video explaining this. I was right!!!😂
"Don't tell DC comics..." ha! Great presentation🌟
Amazing
Thank you! Cheers!
How is it that white dwarfs are able to accrete as much material as needed to explode as a Ia supernova without first expelling that material in successive dwarf novae events?
The progenitors of type 1a are polar (highly magnetic) white dwarfs.
The mass stolen from a companion star is sucked in at the polar regions. It accumulates INSIDE the stellar corpse.
Like a giant pressure cooker, they all have the same breaking point, the same interior capacity (230 million Gauss).
The chandrasekhar limit is the net minimum mass of a pulsar. It has nothing to do with the explosion.
The progenitors of type 1A are polar white dwarfs (like AN Ursae Majoris B.)
The chandrasekhar limit has nothing to do with why the explode. 1.44 S.U. is merely the minimum net weight required to form a pulsar. 🤠✌️
Doc: many limits are at play for our earth's elemental abundance. It does have to do with the chandrasekar limit in white dwarfs. In white dwarfs it is the electron degeneracy pressure, but in neutron stars it is the oppenheimer volkof limit due to neutron neutron or nuclear stiffness not electron speed operating. The quarks will reach the limit of being freed at high enough pressure, to form a quark soup. This quark soup can in no way be simulated at this time, but soon maybe. The mass of this limit of nuclear stiffness is between 2.14 & 2.17 solar masses limiting not due to theoretical theory but direct observation. We do not have the maths or theory for this oppenheimer limit exactly at this time. Also it is thought that spin angular momentum can hold this up to make the exact number unknown.
When a white drawf explodes, does it make it the brightest light in the universe? Can it be seen?
Yes and yes!
Wonderful Thank You Sir
Welcome!
I'm going a bit crazy here. The slide (15:08) says "as the density rises the temperature does not increase" in reference to white dwarfs is that a mistake? Did you mean to say the pressure does not increase? I thought this whole thing was about how the temperature increases to a point that it starts to ignite carbon oxygen burning. If the temp doesn't increase how does it reach a new ignition point?
For white dwarfs, at their high density, a new gas law takes over:
• Pack many electrons into a tiny volume
• These electrons fill all low-energy states
• Only high-energy (high-pressure) states left
Result is a “Degenerate Gas”:
• Pressure is independent of Temperature.
• Compression does not lead to heating.
This means that the objects could, in principle, be very cold but still have enough pressure to maintain a state of Hydrostatic Equilibrium.
During this time, while the electrons are degenerate, the nuclei are still "classical", so they can get hotter until their interaction with the degenerate electrons has enough energy to "lift the degeneracy" and change the state back to a more classical regime. That's the reason for the "helium flash" in AGB stars. Watch my video about the evolution of solar-mass stars. I talk about this in greater detail.
this is nice i’d love to be your student in the future
You can simply watch the entire class in order: www.jasonkendall.com/
Hey dude, do white dwarfs produce magnetic fields that can be detected by the technology that we have now? I am so darn curious about the correlation between magnetic fields and the rest of matter, because it seems to be from my point of view and observations that magnetism is just as important. Static electricity creates magnetism, right? I'm not trying to be a troll I'm just bored and I love astronomy
Aesome
My question is; to what extent have you been able to measure expansion between the earth and our moon?
Two responses: One, there is no effect of the universe's expansion on the size scale of the solar system. It's MUCH smaller than a Megaparsec. But, the recession of the Moon from the Earth is measured, and is the effect of the equiparatitioning of energy due to the actions of the tides. As the Earth's rotation slows to meet the month, and the month's length shortens to meet the day, the Moon drifts outward to balance out the orbital energy.
There is now evidence that there are several classes of Type Ia supernovae one type the single degenerate class happens as you described by mass transfer back and forth as a binary pair ages until a white dwarf reaches the Chandrasekhar limit are also able to form by the merging of two white dwarfs that exceed Chandrasekhar limit. The latter type of type Ia supernovae adds a complication to using type Ia supernovae as white dwarf mergers can actually exceed 1.44 solar masses depending on the mass of the two white dwarfs. They have resolved this issue by determining methods to tell the two types of type Ia apart but it shows how much more complex the situation has gotten. Two further weird oddities are type Iax where the star accretes helium which can result in a weaker explosion that may potentially be weak enough that some part of the star can survive.
arxiv.org/pdf/1901.05461.pdf
Another really weird white dwarf system is the until recently theoretical super-Chandrasekhar mass carbon-oxygen white dwarf where two massive white dwarfs merge together with a resulting mass sufficient to hold together and avoid collapse due to the ignition of carbon fusion in its interior. Earlier this year a team of Russian astronomers published in Nature that using Gaia parallax measurements we able to identify the WO type "Wolf Raynet star" WS35 is 3.07 kpc away and is most likely one of these stars that will eventually undergo a core collapse type Ic supernovae and likely a neutron star remnant.
arxiv.org/abs/1904.00012
I enjoyed the “no va” joke…
There is a joke about a kid who bought a new Chevy "No-va" (A Chevy that doesn't go i.e. broken!)
I like to think I have a fairly decent grasp of this material, but I keep questioning one main thing. When we talk about inflation and the acceleration of the universe, it always goes back to charts showing that the further away we look (aka the further back in time we look) the faster the universe is expanding. I guess I am just not grasping this simple concept, because I would expect to see galaxies further away moving away faster due to the fact that those images are further back in time. I would expect to see faster movement closer to the beginning of an "explosion" than (further away / earlier in time, in relative terms) than I do looking at objects closer. Am I just missing that the time adjustment for distance is compensated for in these diagrams? Because if not, then this is what I would expect to see in an explosion that is slowing down currently.
There is no center to the expansion. So there is no explosion.
@@JasonKendallAstronomer Fair enough and certainly a true statement. But that still does not clarify my confusion. If expansion was slowing, then I would expect that as I look at galaxies further away (aka, further back in time), I would expect to see them moving faster than the galaxies that are closer or more recent in time.
@@3DMatterMakers yes and that is what those Nobel prize recipients expected to see as well...they were as surprised as anyone when they found that the galaxies weren't moving away as fast as they had thought...
Fascinating, where do we get all the elements between magnesium , silicon and iron , I don’t see any mechanism for the production of eg: vanadium
Usually in supernovae or neutron star collisions/kilonovae.
@22:15, what is this seed?