The formation of supernova

[tonogam]

The star ceases to generate energy in the core when extended nuclear fusion results in Iron being formed. Because of this, the core collapse and experience extensive gravitational forces to form a neutron star.<br /><br />Supernova explosion occurs when the collapsing material rebounds off the neutron star, resulting in a shockwave. In addition, by popular convention, massive amounts of neutrinos are being emitted from their core and transmit a fraction (1%) of their energy as they passes through the star, the star is being obliterated, and resulting in a supernova convention.<br /><br />According to many simulations, the process of neutrinos transmitting energy could not be simulated, because neutrinos pass through material so easily that there is no transfer of momentum.<br /><br />I have a few questions to this:<br /><br />1. How could there be a supernova explosion when there is no neutron star, but instead a black hole in the “core”?<br />Is the simple answer that the supernova explosion happens before the black hole is being formed, when there is a similar rebound of stellar material off the neutron-degenerate material in the core?<br /><br /><br /><br /><br />

 

[tonogam]

http://skytonight.com/news/3310836.html<br /><br />In this article, there is a hypothesis that there is some acoustic mechanism in the core that aids in exploding the star to smithereens.<br /><br />Can anyone explain what is an acoustic wave? Is it similar to the sound wave, when atoms oscillates?<br /><br />Many thanks in advance!<br />

 

[abhinavkumar_iitr05]

Dear TonoGam what I know the supernova is a stage before the formation of neutron star just after the Red Gaint Phase.The Red Gaint Explode with release of enormous amount of energy if the mass of the collapsing star is more than that of 1.44 times that of Solar mass ie Chandrashekhar's limit.If want to know more then do read the life cycle of star.

 

[tonogam]

Hi abhinavkumar,<br /><br />thanks for responding...<br /><br />What I am researching on is the fact that things are still murky with regards to what is the process that causes the supernova explosion to occur.<br /><br />According to many simulations, the shockwave that comes from the rebound of the neutron rich core peters out, instead of obliterating the star into pieces.<br /><br />There are two articles that propose some of the mechanisms that may result in supernova explosion. Let me know if you are interested and I can post the relevant links.<br /><br />Gam

 

[tonogam]

Hi steve,<br /><br />thanks for your reply.<br /><br />Actually I did do some research for this past couple of day, with regards to supernova already.<br /><br />I did ask around with regards to my first question. Apparently, the phase which a black hole is formed from a neutron rich core is later than that of a formation of a supernova.<br /><br />My confusion arises when I combined the above 2 phases together, therefore I was wondering why in the first place there was a rebound of stellar materials, since a black hole is going to be formed.<br /><br />Okok. Right now I am focussing my research on the mechanism that powers the shockwave.<br /><br />According to the "The Supernova Story", the shockwave that results from the rebound of stellar materials from the neutron rich core is not strong enough, and would peter before it reaches the surface.<br /><br />The conventional wisdom is that this shockwave is powered by the massive amount of neutrinos being produced by the core because of the extremely high temperature. Otherwise known as neutrino-reheating mechanism.<br /><br />Apparently this mechanism doesn't work very well under simulations and testings. As in the previous case, the shockwave would peters before it reach the surface as well.<br /><br />Currently I am trying to understand why neutrino reheating fails.<br /><br />This is a webpage that details the error.<br /><br />http://www.astro.uni-bonn.de/~perni/science/sne/sne.html<br /><br />Unfortunately my physics is not strong enough to comprehend what it is trying to say when it reaches the "neutrino mean path" part and the "neutrino interactions".<br /><br />In other words, I am at a loss with regards to the neutrinos interactions part.<br /><br />Anyone could explain? Many thanks!

 

[newtonian]

TonoGam - Well, my physics is not so good either, but I certainly can comment on one of the excellent links you provided, and then add some independent comment:<br /><br />“When the mass of the iron core exceeds the maximum for which the electron degeneracy pressure can support the core, the core begins to collapse gravitationally. This accelerates into a catastrophic collapse on a timescale of less than a second because of pressure loss associated with the dissociation of iron nuclei by high-energy gamma rays and the production of neutrinos that escape the star in the initial phases of the collapse. The collapse proceeds to subnuclear densities, where the stiff nuclear equation of state causes the core to bounce.”<br /><br />OK, I do not know what the “stiff nuclear equation” is? Do you?<br /><br />Obviously that is critical since it causes the bounce that opposes collapse into a black hole.<br /><br />And the shock waves apparently proceed from this bounce.<br /><br />Now commenting on link details:<br /><br />Initial collapse due to exceeding Chandrasekhar limit produces much heat which produces high energy gamma rays which decay Iron to 13 Helium nuclei and 4n – would that be 4 neutrons or 4 neutrinos – there is where I get lost!<br /><br />Positron and electron annihilation also produces 1n – I am going to assume (correct me if I am wrong) that the n is a neutrino, since the link then states the neutrino has a long mean free path.<br /><br />Mean is, of course, average – and neutrinos would, I assume, be free because they pass through even extremely dense mass. That’s an educated guess, btw.<br /><br />Now, as I read on this is evidently correct, but short (wavelength not path?) neutrinos are trapped, not free. <br /><br />I know there are different flavors of neutrinos, if this has any bearing on the results.<br /><br />Also, I assume neutrinos could have different energies due to their causal origin, which should effect whether they could be trapped or become free. I assume en

 

[abhinavkumar_iitr05]

Yes my friend do send the link so that I can be well aware about the question what u want to know

 

[alokmohan]

Read degenations seriously and you will know.

 

[tonogam]

Hi abhinavkumar,<br /><br />thanks.<br /><br />This is a webpage that explains why the neutrino reheating doesn't work.<br /><br />http://www.astro.uni-bonn.de/~perni/science/sne/sne.html<br /><br />This is the paper that proposes the acoustic mechanism, that would blow the star into bits.<br /><br />http://arxiv.org/abs/astro-ph/0510687<br />The paper also pointed out why neutrino reheating doesn't really work out.<br /><br />Thanks a lot for any help! Appreciate it a lot...<br /><br />Would continue to read up...<br /><br />Gam

 

[newtonian]

TonoGam - OK, no comments on my attempt to answer your questions?<br /><br />Or no answers to my questions?<br /><br />On your question about acoustic waves, you might find the recent Scientific American article on the Cosmic symphony which may be largely responsible for structure in our universe.<br /><br />I will see if I can dig that up for you.<br /><br />It is a shock wave, btw.<br /><br />But it has harmonious overtones similar to a strativarius violin.<br /><br />There may be some similarities between the possible singularity at the origin of our universe and possible singularity black hole involvement with supernovae shock waves.<br /><br />Of course, this may be evidence that it is not a true singularity at all!

 

[newtonian]

TonoGam - OK, it is the February 2004 Scientific American - two articles, one entitled "The Cosmic Symphony."<br /><br />An excerpt summary:<br /><br />"New observations of the cosmic microwave background radiation show that the early universe resounded with harmonious oscillations." - Sciam, 2/04, p. 44.<br /><br />The article goes on to show that the 1990 satelite COBE measured slilght variations in the CMB(R) [= Cosmic microwave background radiation] amounting to one part in 100,000 [= .001%].<br /><br />That was predicted by big bang models.<br /><br />Further data comes from the WMAP [= Wilkinson Microwave Anisotropy Probe] probe launched in 2001.<br /><br />The CMBR variations are what was predicted, but the article goes on to say:<br /><br />"The process is analogous<br />to determining the construction of a musical instrument<br />by carefully listening to its notes. But the cosmic symphony is<br />produced by some very strange players and is accompanied by even stranger coincidences that cry out for explanation." - Sciam, 2/04, pp.44, 46.<br /><br />The article then goes on to show that the cause and effect mechanism involved literal sound waves.<br /><br />Acoustic waves are, of course, sound waves.<br /><br />There is much more - it is a very interesting article.<br /><br />Do you have access to the article to study it? <br /><br />Suffice it to say that the article describes mechanisms which caused the sound waves.<br /><br />The article also refers us to another article in the same issue of Sciam entitled "Reading the Blueprints of Creation."<br /><br />The article also details the fact that these sound waves have such beautiful harmonious overtones<br /><br />I don't know about you - but to me the awesome beauty of both supernovae and the actual creation of our universe is amazing!<br /><br />I hope that answers your question about acoustic waves.<br /><br />I should just mention that inflation theory is favored in the above since all the sound waves were produced at once. Also that th

 

[newtonian]

TonoGam - You would probably also find of interest the October, 2006 Scientific American article entitled "How to Blow up a Star."<br /><br />This is, of course, concerning supernovae.<br /><br />The overview:<br /><br />"It is not as easy as you would think. Models of supernovae have failed to reproduce these explosions—until recently."<br /><br />I have not studied the article myself yet - just letting you know about it.<br /><br />Do you have access to it?

 

[tonogam]

Hi,<br /><br />I believe that the decomposition of Iron is into neutrons and Helium.<br /><br />The Iron at this point of time is being broken down into individual atoms, aborbing heat in the process.<br /><br />As it is broken down, the core becomes somewhat neutron rich and compact, such that it is neutron degenerate matter.<br /><br />Similar to electron degenerate matter, it has a limit, that is if the mass of the core is too high, then the repulsive forces of the neutron isn't enough to counter the gravitational forces, it would proceed to form a black hole.<br /><br />I would speculate the "stiff nuclear equation" refers to the proximity of the neutrons in the core, which results in the repulsive nature of the core towards infalling stellar material.<br /><br /><br />For the rest of your comments/answers/questions, I don't really much to add. Ha, don't know what to say also.<br /><br />Thanks for your answers Newtonian.<br /><br />

 

[newtonian]

stevehw33 - No comment except appreciate your time and knowledge &/or research.<br /><br />I will comment in time.<br /><br />Meanwhile, I hope to add data from the above Sciam article and see how it compares with your information.

 

[newtonian]

TonoGam - Hi back!<br /><br />I hope to take a short time and add some info as per above.<br /><br />Meanwhile - your welcome.

 

[newtonian]

TonoGam - Some notes on the Sciam article and also my own variant model which could also account for supernovae with no hydrogen in their spectra:<br /><br />Ok, Sciam notes two scientific speculations that proved to be right on causes of supernovae, since there is more than one type of supernova.<br /><br />Fritz Zwicky and Walter Baade speculated the cause was gravity.<br /><br />To wit: A star implodes to the size of an atomic nucleus, and in the process releases a vast amount of potential gravitational energy which blows the rest of the star apart.<br /><br />Fred Hoyle and Willy fowler speculated on an alternate model where the cause was like a thermonuclear bomb. <br /><br />The model goes:<br /><br />Star first exhausts its hydrogen fuel, then its helium, then its carbon and oxygen. The latter releases a titanic pulse of energy and also produces nickel56. The latter produces the supernova afterglow.<br /><br />That was 1938 and 1960 respectively. Now we have observational data to confirm details of both models.<br /><br />Supernovae with no hydrogen in their spectra include Type Ia which do stem from thermonuclear explosion.<br /><br />Type Ib and Ic also have no hydrogen in their spectra, but this is apparently due to collapse + shedding outer hydrogen layers.<br /><br />I would add my own speculation that some stars may actually burn virtually all of their hydrogen due to mixing of core and outer layers due to various causes of mixing – notably differential rotation in different layers and also motions of ions deep within stars which causes magnetic dynamoes such as in our sun which causes very hot coronas such as in our sun.<br /><br />The latter is my own model, btw, and is quite divergent from standard stellar evolution models which posit zero mixing of core and outer stellar layers and therefore posit that stars do not burn most of their hydrogen.<br /><br />I postulate that stars can have very variable properties, some indeed conforming to the standard model, but others q

 

[tonogam]

Hi Newtonian and Steve,<br /><br />Thanks for your quick response. Couldn't imagine myself posting messages of such length.<br /><br />Could see the effort that you all have put in to answer my queries.<br /><br />I am actually rushing my assignment now. I would promise to upload some of my understanding within the next 24 hours.<br /><br />Gam