Astronomers have found the first stars we know of in the universe. They were made about 13.7 billion years ago, which is almost the beginning of time.
By looking at what they left behind, we can learn more about the early universe.
Using the Very Large Telescope in Chile, an Italian team was able to figure out what the ash was.
They discovered them by observing the light from quasars, which are very bright objects at the heart of distant galaxies.
Professor Stefania Salvadori from the University of Florence in Italy, who was the lead author of the study, said: “Our discovery opens up new ways to indirectly study what the first stars looked like.”
Quasars are black holes that emit powerful jets of energy from both sides.
As light moves, it passes through clouds of gas that, depending on their composition, absorb certain wavelengths.
The researchers used this absorption to find three strange clouds of gas about 25 billion light-years away and nearly 25 billion light-years from Earth.
New Scientist says they saw them as they looked about two billion years after they were born, which was more than 11 billion years ago.
When a star explodes in a supernova, it often leaves behind clouds of gas.
But scientists believe that some of the first stars would not have fully exploded, leaving their cores and the heavier elements within intact.
These explosions would have created clouds high in carbon, oxygen, and magnesium, but little or no iron, unlike clouds of more powerful explosives.
The researchers found the same thing. Chemically, these faraway things that are more than 13 billion years old are very different from younger stars like our sun.
Their finding will give us a better idea of how stars, planets and even the most basic elements are formed.
In the early days of the world, there were only very simple things like hydrogen and helium.
The first stars were only made of these things. Over time, their nuclei got so hot that simple atoms slowly turned into heavier elements like carbon, oxygen, magnesium, and eventually metals.
Later generations of stars formed from gas clouds with these larger atoms, and most of the stars scientists study today are filled with metals like iron.
About 98% of our sun is made up of hydrogen and helium, but there are also trace amounts of iron, neon, and carbon.
No one has looked directly at the first metal-poor stars. Most have long since disappeared or burst.
But if experts look billions of light-years away, they can still see some of its dusty remains.
Prof. Salvadori said: “The clouds were very low in iron and other metals but high in carbon, oxygen and magnesium. This is exactly what would have been left after the first stars ran out of fuel and exploded.”
This is consistent with what we already know about the origin of stars and could provide insight into how young stars like those in the Milky Way are created.
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