Science
Astronomers believe they found signs of the earliest stars in universe
In the beginning there was the big bang, and from the big bang sprang forth what we now understand as the Universe. All of it was faster than the blink of an eye. Actually, even that comparison is too slow to explain how fast it all went down.
Making even light look slow in comparison, the big bang occurred in an instant and led to a rather hot universe. It took about 400,000 earth years for the universe to cool down. And all this while there was hardly anything except hydrogen gas.
And in due time, stars formed and a couple hundred million years later, galaxies followed suit.
But can we know exactly when the first star was formed? Well, it seems like the scientists are closer to cracking that one than ever before!
A combined team of experts belonging to MIT and Arizona State University seem to have achieved the impossible!
Stars are said to have formed after the big bang ranging from 100 to 700 million years post that cosmic event. When gravity started acting on the hydrogen gas, making clumps of it pull together and collapsing in on themselves, leading to fusion and eventually to stars. In this process, hydrogen absorbed cosmic radiations (a byproduct of the big bang) and thus could be detected as a shadow in certain radio frequencies.
Scientists have been trying to narrow down the timeline of what they call the Epoch of Reionization (EoR) or in layman terms – when did the first star appear?
Do you know, the stars you see at night, might in fact be long dead. Because the light from the stars takes a long time to reach us, and this we see their past image (long past) instead of the current one. Sun is the closest star we have and yet its light reaches us in 8 minutes.
So, even the great Hubble telescope can only show us what has been in the space and it can look up to 13.4 billion years back.
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Since trying to locate the first star visually can be futile, scientists have instead opted for listening for it via radio signals. But that’s not easy either. The entire universe is making constant noise and within that noise they had to narrow in on one particular signal which is immensely similar to one which is made right here on earth. This is like trying to hear a mouse squeak while you have a room full of crickets. For doing so, they set up their base at Murchison Radio-astronomy Observatory in Western Australia. The project was titled EDGES (Experiment to Detect the Global EoR Signature).
The genius instrument looks like a plain old dining table, but took 12 years to be calibrated, but it did it’s job. They detected a signal and sent nearly two years cross checking it to make sure that it wasn’t some error or haywire signal from right here on earth. The band that gave them a number about the first star’s formation was of a frequency ranging from between 50 megahertz to 100 megagertz. The final number came out to be approximately 180 million years post the big bang.
But contrary to the expectations, the universe’ expected temperatures did not corroborate with what they found to be comparatively colder climates. Upon further research it was proposed that the reason for this drop in temperature is dark matter. Dark matter is as yet invisible for us, but the universe has been postulated to be compromised of 25% of dark matter.
This is a huge success because it is the closest that astronomers have come to locate the formation of stars. Of course this experiment is the only one of its kind so far and thus need a lot of follow ups and support from other experiments for it to be non negotiable.
We have come to the finding of events approximately 380000 post the big bang moment.
A lot more research is necessary to get information beyond that and it is likely that it would be many years from now that further advances can be made in the field.
The birth of the first stars:
Image source: Sun/NASA/CXC/M.Weiss
