Cosmic dust riddle breakthrough: Study tackles stuff of the universe Astronomers have long wondered where all the strange dust that hangs about in space originates. They're also interested in how all the cosmic dust clouds form despite all the solar flares, supernovas and other potentially dust-blasting events. A new study that was published in Nature this week may provide some answers. The …
Thumbs up for taking a new look at something I'm sure a lot of people have looked at and thought a)I wonder why that happens (and thought no more about it) or b)They probably worked this out years ago (but I don't know where to find the answer).
Now there is an answer (well perhaps the start of a fuller explanation?)
This post has been deleted by its author
(Sorry Neil, my withdrawn post made an incorrect assumption about the subject you were asking about.)
It may be that the shockwave forces 'order' onto the hot, dense and diffuse cloud, thus inducing a phase change and effectively 'flushes out' thermal energy. An expert might come along if we wait a while.
"...BUT after it has been compressed the higher density gas can cool off much faster"
Thanks for the clarification. I'm grateful because it means I can still trust my bicycle whose tyres will heat up when I force air into them.
(I never bothered about the speed with which it then cools down again.)
"Thanks for the clarification. I'm grateful because it means I can still trust my bicycle whose tyres will heat up when I force air into them."
The science says that if you force enough air into the tyres, they will get hot enough to become lighter than air and you will then be able to fly.
: )
A star is a fairly dense ball of gas (Sun's average is about 1.6 x density or water). When the star's core finally collapses not all of the star gets to form the remnant neutron star/black hole. There is a rebound shock wave generated in the remaining gas (now going outwards) which is the explosion blowing it all away. When this fast moving gas hits the shell(s) of gas and dust previously expelled from the star it forms the shock wave. It's this that generates the photons seen by us and other wavelength instruments; the photons from within the star are adsorbed by it's gas and don't get seen.
All elements heavier than iron are generated during the rebound compression of the non core part of the star. Normal fusion can't 'burn' heavier than iron even in massive stars.
During the actual core collapse massive numbers of neutrinos are generated; these are not adsorbed and as they move damned near c we see them first and then the visible flash later when the shock wave eventually hits the shells and generate broad spectrum photons.
By the by, current thoughts are that some forms of dust and mixed element molecules are formed by quantum-chemistry in gas in the colder parts of space. Low temperature = slow moving and gives time for electron shells to interact when they are close, not like our normal terrestrial chemistry where they have to based into each other with heat (fast brownian motion).
Sorry but I don't rate the clarity of the article much.
"During the actual core collapse massive numbers of neutrinos are generated; these are not adsorbed..."
According to the main theory they sometimes are, and are responsible for the bulk of the visible explosion:
http://en.wikipedia.org/wiki/Supernova#Core_collapse
"Sorry but I don't rate the clarity of the article much."
Thanks for the explanation. It was quite helpful. Some of the article goes beyond not being clear, though.
Once the hydrogen is all gone and no more energy can be extracted from the fusion process, the star dies and giant clouds of gas....
No, there's still hydrogen left at that point and fusion is still producing energy, just not enough to maintain equilibrium with gravity. What are those "giant clouds of gas" mostly made of?
Supernova were picked as the source of cosmic dust quite some time ago, though the process described in this article may be a new discovery. The first photos of cosmic dust creation were captured in January of this year:
https://public.nrao.edu/news/pressreleases/alma-images-supernova-dust-factory
http://www.bbc.com/news/science-environment-25633545
under zero gravity the main attractive force are electrostatic forces.
and on a massive schale even with huge stellar blasts, it doesnt matter, the moving of particles will create elctromagnetic fields, and particles in such environments atrack each.
Huge stellar blasts will only shake those fields more, and thus create more charge.
If those scientist would have taken some looks to experiments allready done in the space shuttle they would have know this.. (a few years ago)...
There does seem to be a number of errors in this account, which I hope is not a factor in the original article in Nature. To assert that a star 'dies' when it has used up its store of hydrogen, is incorrect. If it was correct, the universe would consist only of the light elements. No, fusion continues of the heavier elements after depletion of hydrogen at its core. Fusion can deliver energy up to the mass of iron, and does. The snag is that the amount of energy diminishes with increasing mass. The latter stages coming quicker and quicker. The final effect is not an explosion, but a collapse. The amount of energy released in this phase feeds more reactions, whilst the superabundance of neutrons are absorbed by the heavy elements to create elements heavier than iron, up to and past the transuranic elements. The subsequent explosion that we see as a supernova, is, in effect a 'dead cat bounce'
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