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Supernovae fans may find this of interest, I know I did:
http://arxiv.org/abs/astro-ph/0402404
http://arxiv.org/abs/astro-ph/0402404
meteor said:The paper says that quark stars should be a mixture of up, down, and strange quarks. I wonder why is not permitted the presence of charm, top and bottom quarks
This has to do with what is referred to as the neutrino opacity temperature [~1MeV]. Neutrinos cannot escape from the stellar core above this temperature.meteor said:So, I keep reading the article and then it's mentioned the fact that neutrinos are trapped in the interior of a newborn neutron star. This phenomenon is called neutrino trapping. What is the nature of this phenomenon? Neutrinos hardly interact with anything, how can they become trapped?
because ... ?Chronos said:This has to do with what is referred to as the neutrino opacity temperature [~1MeV]. Neutrinos cannot escape from the stellar core above this temperature.
meteor said:http://xxx.lanl.gov/abs/astro-ph/0410728
this appeared today. Is a unified model for short GRBs and long GRBs. According to this model, both kinds of GRBs arise from the same phenomenon (high energetic supernovae). The difference is that we are viewing the jet from different angles. I want to remind that the scientific consensus nowadays is that long and short GRBs arise from different phenomena
habitually was thought that long GRBs arise from hypernovae, and short GRBs from a different process (e.g. the collision of two neutron stars)define "DIFFERENT PHENOMENA"
meteor said:habitually was thought that long GRBs arise from hypernovae, and short GRBs from a different process (e.g. the collision of two neutron stars)
north said:in a hypernova, if i understand what your thinking here, is a star which had an imbalance. and the imbalance causes the star to implode. the explosion i suspect is the point of instance with which the balance was broken enough that instead of moving Out from the center of the galaxy, it is now moving in. this then sets up the building of a black hole.
in the collision of two neutron stars. to me at this point i cannot say wether short GRBs are not from the collision of two neutron stars. but i look at it this way. if two neutron stars collide, since they are of the same wavelength,
they will meld into each other quietly(since they are on the same wave length no energy escapes but energy is absorbed). therefore no gamma rays produced. this then leads to WHAT are GRBs,of any length, and that leads to the study of Plasmas and Cosmic Plasmas.
a couple of sites are; www.theuniverse.ws[/url] and [url]www.plasma.org[/URL]
enjoy![/QUOTE]north, thanks for your posts.
However, and perhaps it's just me, but there seems to be considerable confusion in your posts ... For example, the collision of two neutron stars has been extensively modeled, and it does most certainly produce gammas, copious quantities of them. The key question is how well the gamma (and X-ray, and optical, and ...) signature matches the observed short (or long) GRBs (or not). Similarly, whether the short GRBs are merely the first, most violent, sign of a 'flare' on a magnetar can likewise be wrestled with by comparing the observed time and wavelength data against theoretical predictions (there are other tests too).
Note that whether it's colliding neutron stars, hypernovae (or merely common supernovae), magnetars, ... in ALL cases it is plasmas which give rise to what we 'see' (exception: neutrino emission is due to processes that take place within nuclear material, and are only 'plasmas' to the extent that the term has been generalised to cover a completely different physical regime ... the 'quark-gluon plasma', for example).
QUOTE=Nereid]north, thanks for your postsHowever, and perhaps it's just me, but there seems to be considerable confusion in your posts ... For example, the collision of two neutron stars has been extensively modeled, and it does most certainly produce gammas, .copious quantities of them. The key question is how well the gamma (and X-ray, and optical, and ...) signature matches the observed short (or long) GRBs (or not). Similarly, whether the short GRBs are merely the first, most violent, sign of a 'flare' on a magnetar can likewise be wrestled with by comparing the observed time and wavelength data against theoretical predictions (there are other tests too).
No. IIRC, other than a vague, possible match to the timescale, nothing observed comes anywhere close to the classic Hawking exploding (actually, evaporating) primordial BH.Garth said:GRBs - May they be exploding primordial back holes a la Hawking?
Garth
Hmm, not sure what this meansnorth said:i look at it this way, first, we know that the essence of all matter is high energy plasma(non-particle, if it is particle i will say so) and that as it cools this starts the producing of particles, being as well that the other three states are electrically neutral.
lots rolled up here; one at a time:where ever plasmas are present they produce huge amounts of electromagnetic radiation,x-rays and gamma rays, this then according to the Cosmic Plasma people, is caused by the heating of free electrons, to about 1million degrees. this then is the realm of hot magnetized plasma.
You may be right. However, the challenge, should you choose to accept it, is to show that the physical processes you describe result in gamma bursts with the spectral and time profiles that are observed (oh, and the X-ray and optical and radio spectra and time profiles too). You do understand why this is important, don't you?so now we have GRB which are short and long, these i think are not caused by the colliding of neutrons but the interaction of there magnetic fields,in which their collective free electrons and tightened magnetic field lines are coming in contact before the neutron cores themselves come in contact and sometimes there are many free electrons and sometimes there are not hence,long and short bursts. as well, from what i found so far these bursts are extremely short in duration.
A supernova is a powerful explosion that occurs at the end of a star's life. It releases a tremendous amount of energy and can outshine an entire galaxy for a brief period of time. GRBs (gamma-ray bursts) are highly energetic explosions that are thought to be associated with the deaths of massive stars, which can also result in supernovae.
GRBs are important because they are the most powerful explosions in the universe and can provide insight into the physics of extreme events. They also serve as valuable tools for studying the early universe and the formation of elements.
Scientists use a variety of tools and techniques to study supernovae and GRBs, including telescopes, satellites, and computer simulations. They also analyze the light and other radiation emitted from these events to learn more about their properties.
Through studying supernovae and GRBs, scientists have learned about the formation and evolution of galaxies, the production of heavy elements, and the physics of extreme environments. These events have also provided evidence for the expansion of the universe and the existence of dark matter and dark energy.
Fans can stay updated on the latest research by following reputable science news sources, subscribing to scientific journals, and following social media accounts of scientists and organizations involved in this research. They can also attend scientific conferences and talks to learn about new discoveries and breakthroughs in the field.