Astronomers Find Stars That Are Older Than The Universe. How Is This Possible? - Alternative View

Astronomers Find Stars That Are Older Than The Universe. How Is This Possible? - Alternative View
Astronomers Find Stars That Are Older Than The Universe. How Is This Possible? - Alternative View

Video: Astronomers Find Stars That Are Older Than The Universe. How Is This Possible? - Alternative View

Video: Astronomers Find Stars That Are Older Than The Universe. How Is This Possible? - Alternative View
Video: Is the "Methuselah" star older than the Universe? 2024, November
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After reading the title, you probably thought that something is wrong here. But what - a star, the Universe, or something else? If you know how stars work, you can take one, study its physical properties and find out when it should have appeared. Stars go through many changes as they age: their radius, luminosity, and temperature change as fuel burns. But the lifespan of a star, in general, depends only on two properties with which it is born: mass and metallicity, that is, the amount of elements present in it that are heavier than hydrogen and helium.

The oldest stars we have found in the Universe are virtually untouched, and are almost 100% hydrogen and helium left over from the Big Bang. They may be 13 billion years old, and the oldest is 14.5 billion years old.

And that's a big problem, because the universe itself is only 13.8 billion years old, says Ethan Siegel of Medium.com.

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The core of the globular cluster Omega Centauri is one of the most crowded regions with old stars. There may be stars here and 12 billion years old, and the oldest - more than 14 billion years old, and this is a problem, because they are older than the Universe itself.

There cannot be a star older than the Universe itself; otherwise it would have existed long before the Big Bang. But the Big Bang became the source of the appearance of the Universe known to us, from which all matter, energy, neutrinos, photons, antimatter, dark matter and even dark energy came out. Everything in our observable universe began with this event, and everything we deal with today can be traced back to this moment. Therefore, the simplest explanation that stars could have appeared before the Universe itself should be ruled out.

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It may well be that we have incorrectly deduced the age of the universe. We extract it from precise measurements of the universe on a large scale. By exploring a range of features including:

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  • density and temperature defects in the cosmic microwave background, the afterglow of the Big Bang;
  • clustering of stars and galaxies now and billions of light years away;
  • the speed of the Hubble expansion of the fabric of the Universe;
  • history of star formation and galactic evolution;

as well as many other sources, we get a very consistent picture of the universe. It consists of 68% dark energy, 27% dark matter, 4.9% ordinary matter, 0.1% neutrinos, 0.01% radiation and is about 13.8 billion years old. The uncertainty of the age of the Universe hovers around 100 million years, so while the Universe could certainly be a hundred million years younger or older, it is unlikely to reach 14.5 billion years.

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ESA's Gaia mission measured the positions and properties of hundreds of millions of stars near the galactic center and found the oldest stars known to mankind.

There is only one reasonable possibility left: apparently, we are incorrectly estimating the age of the stars. We have studied hundreds of millions of stars in detail at different stages of their lives. We know how stars are formed and under what conditions; know when and how they ignite nuclear fusion; we know how long the various stages of synthesis last and how effective they are; we know how long they live and how they die, different types with different masses. In short, astronomy is a serious science, especially when it comes to stars. In general, the oldest stars are relatively low in mass (less massive than our Sun), contain few metals (elements other than hydrogen and helium), and may be older than the galaxy itself.

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Extremely old stars can be found in globular clusters.

Many of them are found in globular clusters that, for sure, contain stars that are 12 billion or, in rare cases, even 13 billion years old. A generation ago, people argued that these clusters were 14-16 billion years old, which created tension in established cosmological models, but gradually an improvement in understanding of stellar evolution brought these numbers in line with the norm. We have developed more advanced methods to improve our observational ability: by measuring not only the carbon, oxygen or iron content of these stars, but also using the radioactive decay of uranium and thorium. We can directly determine the age of individual stars.

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SDSS J102915 + 172927 is an ancient star 4140 light years from us, which contains only 1 / 20,000 of the heavy elements compared to our Sun, and should be 13 billion years old. It is one of the oldest stars in the universe.

In 2007, we were able to measure the star HE 1523-0901, which makes up 80% of the mass of the Sun, contains only 0.1% of the solar iron and is believed to be 13.2 billion years old in terms of its abundance of radioactive elements. In 2015, nine stars were identified near the center of the Milky Way, which formed 13.5 billion years ago: just 300 million years after the Big Bang. "These stars formed before the Milky Way and the galaxy formed around them," says Louis Howes, co-discoverer of these ancient relics. In fact, one of these nine stars has less than 0.001% solar iron; This is the type of star that the James Webb Space Telescope will be looking for when it starts operating in October 2018.

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This is a digitized image of the oldest star in our galaxy. This aging star HD 140283 is 190 light years away. The Hubble Space Telescope has specified its age at 14.5 billion, plus or minus 800 million years.

The most striking star of all is HD 140283, informally nicknamed the Star of Methuselah. It is only 190 light years from us, and we can measure its brightness, surface temperature and composition; we can also see that it is just beginning to develop in the subgiant phase to become a red giant later. These pieces of information allow us to infer a well-defined age for the star, and the result is at least alarming: 14.46 billion years. Some properties of the star, such as the iron content of 0.4% of the sun, say that the star is old, but not the oldest of all. And despite a possible error of 800 million years, Methuselah still creates a certain conflict between the maximum age of stars and the age of the universe.

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The Milky Way has not changed for billions of years. But as the stars grow older, the most massive cease to exist, and the least massive begin to turn into subgiants.

It is obvious today that something could have happened to this star in the past that we do not yet know today. Maybe she was born more massive and somehow lost the outer layers. Perhaps the star absorbed some material later, which altered its heavy element abundance, confusing our observations. Maybe we just poorly understand the subgiant phase in the stellar evolution of ancient stars with low metallicity. Gradually, we will deduce the correct shape or calculate the age of the oldest stars.

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But if we're right, we face a serious problem. In our Universe, there can be no star that is older than the Universe itself. Either there is something wrong with the estimate of the age of these stars, or something is wrong with the estimate of the age of the universe. Or something else that we don't yet understand at all. This is a great chance to move science in a new direction.

Ilya Khel