Supernovae usually occur in stars with 10-100 solar masses, rarely this also happened in a star with 150 solar masses - where the core of the star turned into iron
What happens when a giant star - hundreds of times bigger than our sun - explodes? A theory in this regard was developed years ago, but the first observation of such an explosion was made only recently, by a team of scientists from Israel, Germany, the United States, England and China, led by Dr. Avishi Gal-Yam from the Weizmann Institute of Science. The team followed such an explosion (supernova) for a year and a half, and found that the observation corresponds to the predictions arising from the theory of the explosion of stars that are 150 times or more the mass of our Sun. These findings, which may expand our understanding regarding natural limits on the size of stars, as well as regarding the processes of creating the elements in the universe, were recently published in the scientific journal Nature.
"The secret lies in balance" says Dr. Avishi Gal-Yam from the Department of Particle Physics and Astrophysics at the Weizmann Institute of Science. "During the life of the star, a balance is maintained between the force of gravity that pulls its material in, and the heat created by the nuclear reaction at its center that pushes the material out. In the supernovae we know, those of stars 10-100 times larger than our Sun, the nuclear reaction begins with the fusion of hydrogen into helium, as in our Sun. But in stars where hydrogen runs out, nuclear fusion of heavier elements continues until the star's core becomes iron. At this point, since iron atoms do not fuse easily, the nuclear reaction ends - and the balance is broken. In the absence of a force pushing outward, gravity takes over and the mass of the star collapses inward. During the collapse, a lot of energy is released which causes an explosion, and the star throws its outer layers into the vastness of the universe."
But the physical process occurring in a supergiant star is different. In these stars, photons (particles of light) are created so energetic that they may merge with each other and become pairs of particles: electrons and their opposite particles, positrons. That is, particles with mass (electrons and positrons) are created from the photons, which have no mass, which draws energy from the star. Again, the balance is broken, but this time, the star collapses at the point where its core is made of oxygen, not iron. The hot, compressed oxygen explodes in a rapid thermonuclear reaction that destroys the center of the star completely, leaving behind only glowing stardust. "Models of 'couple supernovae' were calculated decades ago, for example by Prof. Zalman Barkat and Prof. Gideon Ravavi from the Hebrew University, and Prof. Giora Shabiv from the Technion," says Dr. Gal-Yam, "but no one knew whether such huge explosions really taking place in nature. The new supernova we discovered fits these models."
By analyzing the information they collected from the new supernova, the scientists estimated the size of the star and found that its mass is about 200 times greater than the mass of the Sun. This result is particularly interesting, because until now many scientists believed that in our part of the universe there are no stars whose size exceeds about 150 solar masses, and it is possible that there is a certain physical constraint that limits the extent of the stars. The findings that emerge from the research of Dr. Gal-Yam and his research partners suggest that supergiant stars are indeed rare, but do exist. It is even possible that even larger stars - up to 1,000 times the size of the Sun - existed in the young universe. "This is the first time we have been able to analyze observations of such a huge exploding star," says Dr. Paolo Mazzali of the Max Planck Institute for Astrophysics in Germany, who led the theoretical study of the explosion. "We were able to measure the amounts of new elements created in this explosion, including newly formed radioactive nickel, whose mass is more than five times the mass of the Sun. Such explosions may be important 'factories' for the production of heavy metals in the universe."
The observed giant supernova is in a tiny galaxy - only a hundredth of the size of our galaxy. Scientists believe that such dwarf galaxies may - for various reasons - be home to such giant stars. Dr. Gal-Yam: "The discovery and analysis of this unique explosion gave us new insights into the maximum dimensions that such massive stars can reach, and into the way in which these giants contribute to the composition of the elements in our universe. We hope to expand our understanding even further when we find new examples of such stars. To that end, we recently started conducting new surveys in large and unknown areas of the universe."
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Yoel Moshe:
The photon is a particle.
The word "unit of energy" can be confusing because it would be possible to conclude that energy is measured in photons, which is not the case.
A photon has energy expressed in its frequency.
The higher its frequency, the higher its energy.
To Michael and Ehud, thank you. Is the photon therefore to be defined as an energy unit?
I would appreciate clarification
Moses
The process is the opposite process to the annihilation of a particle and an antiparticle. For example, an electron and a positron can disappear and produce a photon (massless).
Yoel Moshe:
That's because you haven't heard about the equivalence of mass and energy and that they can be converted to each other.
Can someone give an explanation for, massless particles [photons] becoming massed particles [electrons and positrons''. To me it sounds like a contradiction.
Thanks
Ran:
You can find the answer to your question and many more that you may have on the subject here:
http://en.wikipedia.org/wiki/Supernova
Mainly in the Current models chapter
It has been bothering me for a long time:
How long does such an explosion take?
I mean from the moment it starts until it all dissipates.
Seconds? subtlety? years?
If we look at a hand grenade for example, it is possible to very clearly define the time from the moment the energy is released until the system comes to rest again. It's almost a second, let's say.
How is it in the stars?
Tam's question (maybe):
Is it known when the supernova mentioned in the above article occurred?
During the nuclear fusion of a star, elements as heavy as iron are formed - when all these fusion reactions release energy. Because it is not possible to produce energy from the fusion of nuclei heavier than the iron nucleus - it is the last of the elements formed in the cores of stars by way of nuclear fusion. During the star's supernova, for a short time a tremendous source of energy is created in the star that allows heavier elements to be formed - light particles undergo fusion with the iron and become heavier and heavier elements (nickel, lead, uranium, etc.).
It should be added that most of the radiation emitted in a supernova is not in the field of electromagnetic radiation, but energy emitted in neutrinos - particles originating from the processes occurring in the core of the exploding star, including electrons and protons, created neutrons while emitting neutrinos.
little:
In this sense (of the formation of various elements during a supernova) there is no new information here.
In fact, almost all elements were created during fusion - in stars and supernovae.
http://en.wikipedia.org/wiki/Nuclear_fusion
This is indeed the fulfillment of the alchemists' dream, but unfortunately these are very energetic processes (both the energy necessary for the earth and the energy they create) and we have not yet learned to control and restrain them.
Restraint is not always what we are looking for and the hydrogen bombs will prove this, but when it is not about bombs we probably have more to learn (and probably not from a supernova eruption which is also an explosion).
Another note
For sufficiently large initial stellar masses (see theoretical limits I mentioned in the previous response),
The product that will be a black hole or a neutron star depends on the specific mechanism of the supernova (explosion), how fast it occurs and how many nuclear reactions occur.
But this information is indeed useful, perhaps it will be possible to prepare different building blocks such as iron by investigating how it is formed in the universe. That is, to simulate a kind of supernova only in different dimensions and here we have material =] sounds extremely fascinating...maybe..I'm just a little boy
I will park:
This is not "either a black hole or a super nova"
In fact the situation is the opposite: a supernova explosion almost always involves the formation of a black hole.
A. Ben-Ner:
At the time I saw tables on the matter in Kip Thorne's book Black holes and time warps but a check on Wikipedia shows that there are no absolute numbers on the matter. They condition the formation of the core-sized black hole that remains after the explosion but do not talk about what the mass of the star was before the explosion.
http://en.wikipedia.org/wiki/Black_hole
So when was a black hole formed and not a supernova?
To A. Ben-Ner
In order for gravity to overcome repulsive forces and become a black hole, it needs to be massive
More than 1.4 solar masses, which is the Chandrashankar limit below which the electron degeneracy pressure succeeds
To stop the griotational collapse.
Another limit is the Tolman-Oppenheimer-Volkoff limit which determines when the grotitation is stronger than the neutron degeneracy pressure.
The mass corresponding to the Tolman-Oppenheimer-Volkoff limit is about 3 solar masses.
I don't have enough knowledge on the subject, but another possibility is that the star will collapse soon enough before me
All the protons will turn into neutrons and then a black hole may be formed from a star with a mass less than a limit
Tolman-Oppenheimer-Volkoff.
So much for theoretical limits as far as I know the typical mass for a star turning into a hole
Black is about 10 solar masses.
When you say "larger than" you mean "larger than".
to incognito
A mistake in your words. The benefit to humanity is not from the scientific research or the supernova research, but from the knowledge (!!!) learned and accumulated as a result of the research.
It is possible that the concrete information about the supernova will not be there to help humanity directly and immediately, however, the scientific knowledge acquired by humanity
During the research, about the laws that work in nature, may be useful and useful in many and varied fields and areas that are not even predictable and predictable
in the research phase. There are many examples of this.
did you know The internet network you are using now was developed at the Large Hadron Collider (LHC) in CERN-Switzerland, for internal communication needs between the operators of the accelerator and the researchers who are supposed to analyze the results of the experiments they will conduct in the accelerator. And here, wonder and wonder, even before the experiments began with the accelerator itself, the Internet became a worldwide network of immense dimensions. Even if the LHC is out of use today and not a single experiment will be performed on it, it has already made its enormous contribution to humanity. Not least after the planned experiments are carried out on it.
A question for the "in the know" as far as you are:
How many solar masses, at least, should a star have so that when it reaches the end of its life and explodes in a supernova explosion, its core will become a "black hole"?
In all scientific research there is always help for humanity in any way
But it doesn't seem to me that the study of supernovae helps the human race in any way (knowing new information without need does not necessarily help).