A team of scientists from Israel, Japan and the USA used the Subaru giant telescope in Hawaii to discover the largest and most distant sample of supernovae to date, from which it turned out that the rate of exploding stars 10 billion years ago was greater than expected
A team of scientists from Israel, Japan and the US used a giant telescope in Hawaii to discover the largest and most distant sample yet of supernovae, which are the massive explosions that end the lives of certain stars. The light from these events made its way to us about ten billion years ago, billions of years before the formation of the earth. The light, upon reaching us, allows a view of the universe in its youth. The team members used the supernova sample to conclude that these explosions were five times more common in the early universe than they are today. The study, published today in the journal of the Royal Astronomical Society, was led by a group from Tel Aviv University: PhD student Or Graor, Dr. Dobi Poznansky, and Prof. Dan Maoz. Another Israeli member of the team is Dr. Avishai Gal-Yam, from the Weizmann Institute.
"Supernovae are of great importance", explains Maoz. "They are nature's factories for heavy elements: all the chemical elements in the periodic table that are heavier than oxygen are produced in the nuclear processes that take place in the star, before and during the explosion. The explosions also scatter the fresh elements throughout space, where they serve as raw material for further generations of stars and planets. Thus, supernovae are responsible for the formation of the atoms that make up our bodies, such as the calcium atoms in our bones, or the iron atoms in our blood." Graor adds: "Information about the frequency of explosions, throughout the life of the universe, shows how the chemical composition of the universe changed over time, from the homogeneous combination of hydrogen and helium only, which prevailed in the universe immediately after the big bang, to the chemical richness that surrounds us today."
In astronomy, the farther you look, the earlier you see parts of the universe. But due to the great distance, the light reaching us from the supernova explosion is also very weak. To overcome this obstacle, the researchers used the Japanese "Subaru" telescope (no relation to the car), one of the largest and most sophisticated in the world, located at an altitude of 4200 meters, on the summit of an extinct volcano. The telescope has a huge primary mirror with a diameter of 8.2 meters, with the help of which the little light from the explosions can be collected, and it is endowed with extremely sharp images. To discover the supernovae, the researchers aimed the telescope at one piece of sky, similar in area to the area of the sky covered by the full moon. Each time they imaged the field, they allowed the telescope to collect the scant light from the supernovae over several consecutive nights, creating exceptionally long and deep exposures. In each exposure, the researchers discovered about 40 supernovae that exploded among the 150,000 galaxies in the field. In total, the team discovered 150 explosions, including 12 of the most distant explosions seen to date.
From the data analysis, the team members concluded that the frequency of a certain type of supernovae, those that explode in a nuclear fusion process, was five times higher in the early universe, about ten billion years ago, than today. Thermonuclear supernovae, also called type Ia supernovae, are one of the main sources of the element iron in the universe. Astronomers also use these types of supernovae to measure distances in the universe. At the end of the 90s, they enabled the discovery that the expansion of the universe is not slowing down, as they had assumed until then, but rather accelerating under the influence of a new and mysterious factor that was nicknamed "dark energy".
However, the exact nature of Type Ia supernovae is still not understood, and the identity of the exploding star systems is hotly debated among the research community. The new findings reveal the age range of the stars that can explode as a supernova of this type, thus providing important clues to solving the mystery. The team's results are largely consistent with a scenario in which a thermonuclear supernova is the result of the merger of two "white dwarfs," the dense cores of ancient stars. According to Einstein's theory of relativity, the pair of dwarfs emits "gravitational waves", which leads to a suicidal spin and fusion, ending in a thermonuclear explosion - it is the supernova, whose light then embarks on a long journey through time, on its way to us.
17 תגובות
Amit:
I understand that you assume that I have spent the last two weeks under some rock in a cave in Afghanistan if you refer me to this news.
post Scriptum. You should not have a discussion on this subject with Yehuda.
to Judah,
To continue your analogy, the Earth, Mars, Venus, and the Sun are one of many books. Even though the cover is different, I can always expect to see words/letters common to all the books and use the knowledge I have from the books I've read to create an overarching set of rules, a language, for all the books. This is how ancient writings are also deciphered.
Regarding the G, all the above arguments of masses that interfere with accurate measurement are unfounded, because they can be taken into account. Several variations of the experiment can be performed (in different places, at the depth of the soil, etc...) to confirm the results. Indeed, since the days of Cavendish the constant has changed by less than 2%.
Suppose one of the experiments was wrong, but it is not possible that all the experiments (with different methods, different equipment, different places, etc...) carried out since then are also wrong. ZA that the value must be correct.
Happy New Year 🙂
post Scriptum.
Adi, it is still too early to say for sure, but it is very possible to move faster than the speed of light.
http://www.nature.com/news/2011/110922/full/news.2011.554.html
"It is hard for me to believe that they could accurately measure the gravitational constant on the surface of the tennis ball when all kinds of masses and phenomena are circulating in the measurement environment (Humans and birds, Earthquakes)"
Glin Glin Glin!
And the lucky winner of this week's retarded argument award is…. (drums) Sabdarmish!
The question is over:
(I think that) your problem is in the interpretation you give to our movement. Indeed, nothing can move faster than the speed of light, and we must be moving much slower. But what is important to understand is that nothing can move faster than the speed of light in space. But space itself is expanding. Imagine an ant walking on a balloon marked with 2 dots. The balloon is the universe and the ant is a ray of light that left one point and goes to the other point. Now start inflating the balloon quickly - the ant is still walking at the same pace on top of the balloon, but the distance between the points increases very quickly - there is no contradiction here, the ant has a constant speed relative to the balloon, but there is no law of nature that prohibits us from inflating the balloon under its feet at any speed that we would like
Two comments:
A. Actually what happened is that a few moments after the big bang someone inflated our balloon all at once to enormous dimensions and thus huge distances were created on the surface of the balloon, since then it continues to inflate but at a small rate relative to that stage.
B. Our balloon continues to inflate and the rate at which it does so is accelerating. In the future, a situation will occur where it will spread faster than the speed of light (the balloon inflates faster and faster and the point is moving away from the ant faster than the speed at which it is moving towards it), which means that there will be points in the universe from which light will never reach us, and as time goes by we will see fewer and fewer galaxies.
Michael Rothschild - Thanks for the reference, but I'm looking for an intuitive explanation (if possible) from someone who knows the subject well and is able to explain it simply (I know the Wikipedia version, but the event horizon thing still doesn't sit well with me).
Answer to you:
http://en.wikipedia.org/wiki/Inflation_(cosmology)
to a colleague
If it is sometimes true in biology it does not mean it will also be true in other things. If you've seen a thousand paper books it doesn't mean anything about the next book you see and it may be of a different material (leather, cloth?)
The fact that they were accurate in measuring the gravitational constant does not mean that it was not different in the past. In short, our opinions differ.
And besides, I find it hard to believe that they could accurately measure the gravitational constant on the surface of the ball when all kinds of masses and phenomena (humans, birds, earthquakes) are circulating in the measurement environment.
But it does not matter
The main thing is that we have a good year
Sabdarmish Yehuda
I have a question that has been bothering me for years and I hope someone here has an answer.
If the light reaching us came out 10 billion years ago, then the path it traveled is 10 billion light years.
How was such a distance created between us and these supernovae, if the speed of all of us is significantly sub-light speed, and this in light of the assumption that the big bang from which we all started was 15 billion years ago?
Does it work out in terms of numbers?
* at a level
Although I agree that there is a degree of uncertainty regarding the legality (after all, until a few days ago we thought that the speed of light was the upper limit...), I still do not think that your arguments hold.
There are no shortage of examples of individual discoveries that have been generalized, in the fields of biology, for example, it is customary to study creatures with a simple level of complexity and then adapt the model to mammals, etc., for example studies on different genes.
In cases in biology, the models work because there is a set of basic laws that link everything (this is also very common in mathematics).
Therefore, the models we have about the evolution of the universe (after the first second or in the region of) are accurate, and there are also measurements that confirm these models (such as cosmic background radiation).
In conclusion, there is no failure here, in my humble opinion.
To no one, I don't think there is a constant Fg in the universe, neither today nor then, because the gravitational force experienced by a star/celestial body is proportional to one part of the square of the distance between the bodies, and the bodies are always in motion.
G specifically can be measured on the Earth with great precision, and since gravity is one of the fundamental forces, conclusions can be drawn. Build a model that includes particles/stars that are light years away from Earth.
But, what does affect the universe is dark energy because the universe is growing and not shrinking, because the force exerted by the energy is higher than the total gravitational force in the universe (at the general level and not at the regional level).
And also don't forget that the laws are proven only at the current background temperature of the universe, 2.73 degrees Kelvin and not at the enormous temperatures that existed after the big bang.
Sabdarmish Yehuda
Dear men
I agree with your opinion, but not only. In my humble opinion
The various laws of cosmology have only been tested in the last three hundred years and have been proven with certainty only for distances of no more than the solar system, (a thousand light years), for masses of one solar mass (the solar system) or a few - for example double stars.
To draw conclusions from this about billions of years, billions of light years, and billions of billions of solar masses - absolute certainty?.... This is, in my humble opinion, a grave mistake.
It is true, I know the cosmological principle, but I am afraid that such a "principle", which expresses more the desires of scientists than a scientific principle, does not have the power to change anything in the above facts,
Please respond gently
Happy New Year
Sabdarmish Yehuda
Could it be that the frequency of supernovae in the past was greater because of a greater gravitational constant G?
Or maybe the density of 'donor stars' and white dwarfs was greater.
Better to say in the title: Israeli scientists were partners in the discovery, etc.
Happy New Year
Sabdarmish Yehuda