December 8, 2023

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Scientists find the oldest star

Scientists find the oldest star

discovery He reveals that the “ancestor” of the sun was a giant, and although the giant star exploded as a supernova more than 13 billion years ago, the constituent elements in its core live in the sun and other stars.

So for the first time the mystery of the entire history of stars from the beginning of the universe to the present time is true.

Stars have been burning for billions of years

We live on a planet composed largely of elements like oxygen, iron, silicon, and aluminum, but there wasn’t any in the beginning of the universe.

The Big Bang only produced a lot of hydrogen, a lot of helium, and a tiny bit of lithium—the three lightest elements. The vast majority of other elements that we know of originated in stars.

In its red-hot heart, lighter elements fuse into heavier elements. The fusion of light nuclei provides the energy of the stars. Heavy elements are leftovers from the nuclear reactions that make stars emit light and heat.

The stars that form now contain mostly hydrogen and helium, as well as many other elements, all of which originated in earlier stars.

So there must be a first generation of stars consisting entirely of hydrogen, helium and lithium. Somewhat confusingly, these stars are also known as Society III stars because they are the type of stars that astronomers have recently discovered.

Today, scientists divide stars into three generations, which we can identify by their characteristic elemental composition.

The first generation appeared a few hundred million years after the Big Bang. The second generation arose from the remnants of the first stars, and the stars that formed about 2.8 billion years ago after the Big Bang and up to the present time are considered to be the third generation.

Stars can burn for trillions of years, much longer than the 13.8 billion years the universe has existed. So, in principle, some of the first stars could still exist today.

But the age of stars is determined by their size, and not all stars age that way.

The largest stars are under such pressure and temperature that their fuel burns out in a few million years.

A medium-sized star like the Sun can burn for 10 billion years. This is still less than the age of the Universe, but if some of the first stars were younger than the Sun, the so-called red dwarf stars, they must still exist in our galaxy.

But despite 40 years of searching, astronomers have not been able to find a red dwarf star with the correct composition for a first-generation star: it does not contain heavier elements.

Perhaps it is not surprising that no first-generation stars have been found. Most astronomers believe that the original stars were gigantic and thus burned up within a few million years in the still young universe.

Computer models of star formation in the early universe indicate that hydrogen and helium charges from the Big Bang accumulated in such large, dense clouds of gas that stellar stars more than 100 times the mass of the Sun formed.

Elements formed after fusion in the first stars spread out into the universe as stars burned and exploded as supernovae. Thus, the universe was enriched with heavy elements, which later became part of the next generations of stars.

Over the history of the universe, more and more hydrogen has been converted into heavier elements, and while the first generation had no elements heavier than lithium, the second generation contained up to 0.1 percent of the heavy elements. Many of them are still burning, including in the very center of the Milky Way.

The sun only appeared when the universe was more than 9 billion years old, and it belongs to the third generation. It contains about 1.8 percent heavy elements, while stars that form today have up to 4 percent heavy elements.

When we look far out into the universe, we are also looking back in time, because it takes billions of years for light to travel from the most distant stars to us.

So if you look far enough, you should be able to see the first stars, even though they burned out long ago. But as big and bright as it is, it’s hard to see because it’s so far away.

So a team of astronomers from Japan, the United States and Australia developed an indirect way to find them.

The black hole indicates the early star

Instead of searching for the light of a first-generation star, researchers have now found traces of its end: a supernova explosion. And in this they were helped by a giant black hole.

The black hole itself does not emit light. It absorbs a lot of gas, which is heated to millions of degrees, burns fiercely and eventually disappears.

So the immediate vicinity of a black hole can be viewed as a celestial body called a quasar.

Unlike stars, quasars are so large and bright that they can be clearly seen even at billions of light years away.

For example, quasar J1342 0928 is powered by a supermassive black hole with a mass equivalent to 800 million suns, and now astronomers have found remnants of an original star in its light.

The quasar’s light had been traveling for 13.1 billion years when it was detected by the large Gemini North telescope in Hawaii.

By dividing the light into wavelengths and carefully studying the light’s spectrum, astronomers have discovered that the gas around the black hole contains an unusual amount of iron and little magnesium.

Computer simulations show that a first-generation star with a mass of 280 times the mass of the Sun will explode as an “even-unstable” supernova, producing a gas cloud with many atoms of iron and little magnesium.

This distribution of elements is difficult to explain in any other way. Therefore, astronomers can say with great certainty that one of the oldest stars in the universe ended its days near the black hole.

The red dot is the grandfather of the sun

This discovery supports the theory that at least some of the first stars were giants that burned up very quickly and exploded as supernovae.

Astronomers have not yet given up on the dream of catching a glimpse of the first stars while they are still shining brightly in the sky.

They’re now relying on NASA’s new James Webb space telescope, which is meticulously designed for exploration of the early universe.

Even with a Webb telescope, it would be difficult, but not impossible, to observe individual stars that formed during the first billion years of the universe’s history. In fact, astronomers already have a target — the extremely distant object WHL0137-LS, nicknamed Earendel.

the First telescope images of Arendelle Turns out it might be a star, or perhaps a galaxy of stars, that lit up 12.9 billion years ago.

But more observations are needed before astronomers can be sure that the tiny red dot is one of the first stars to light up the universe – an ancestor of the Sun.

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