According to the researchers, the nebula disappeared about 12 billion years ago
By: Tamara Traubman and New York Times
A gas cloud from a very ancient period was observed for the first time a few months ago from telescopes from Earth - this is what astronomers from the "Sloan Digital Sky Survey," an ambitious multinational project whose goal is to map a large part of the universe and catalog about 200 million celestial objects, reported this weekend.
Scientists believe that after the universe was created about 13 billion years ago in the "Big Bang", a "dark" period prevailed, known by cosmologists as the "Dark Ages of the Universe". As the universe continued to expand and cool, the gases created in the explosion began to form stars and galaxies. "Until the time in question, there were no stars or galaxies. During this period, the matter began to organize, and stars and galaxies began to form," the head of the team that discovered the gas cloud, Prof. Robert Becker, told Haaretz.
At an early stage, when there were still only a few stars and galaxies in the universe, large amounts of gas remained in space, creating a kind of heavy fog made of hydrogen atoms. The fog blocked most of the light rays emitted by the first stars, hiding them. With the formation of more and more stars - the fog disappeared, giving way to the newly created stars.
The researchers in the project believe that they were able to see the last fragments of the nebula left in the universe. This nebula clouded the earliest celestial object observed so far.
This object, known as a "quasar", belongs to a group of objects located at the edges of the universe and emit enormous amounts of light - several billion times that of most suns. The members of the project reported the discovery of the quasar a few months ago, and after further analysis of the received data - they concluded that they had, in fact, also seen the remnants of the ancient nebula. According to one of the researchers, Dr. Michael Strauss, the data collected suggests that the nebula disappeared about 900 million years after the formation of the universe.
According to Dr. Mark Davis from the University of California, just as the fragmentary evidence from the medieval period of human history leaves many mysteries, so the observations of the ancient universe do not solve all the questions and even raise new questions. For example, said Dr. Davis, "How on earth did a beam of light as massive as a quasar form in such a short time from the moment the universe was born? This tells us that we do not really understand enough the details of how galaxies are formed."
* The Hidan website was until the end of 2002, part of the IOL portal of the Haaretz group
