A very pristine star in the universe

The research where the discovery of a star with the name SDSS J0715-7334 was announced was published in the scientific journal Nature Astronomy on April 3, 2026 and the report or summary of this research was published a few days later, on April 15, in the same journal. SDSS J0715-7334 is not extremely far away, in a very very distant galaxy, in fact, although it is not in our galaxy, it is located next to us, in the Milky Way.

SDSS J0715-7334 is located in the halo of the Large Magellanic Cloud, which is a satellite galaxy of our Milky Way galaxy. SDSS J0715-7334 is about 80,000 light years away and is a low-mass red giant, or rather, it is now a low-mass red giant because in its youth this star was similar or slightly less massive than the sun, now it is in its final phase, in its old age, in the red giant phase, a phase that our sun will also reach, but the question is, how do you know that it is so old and so pure?

Well, because astronomers have analyzed its light and have discovered that its metallicity index, that is, the amount of metals it contains, is very low, it is practically free of metals, it is 10 times poorer in metals than the most extreme galaxies observed by the James Webb space telescope in the early universe and it contains 20,000 times less metals than what we would find in the Sun and in the solar system as a whole.
Its carbon abundance is also very low, making this star almost pristine with a composition dominated by hydrogen and helium.

SDSS J0715-7334 must have been born within the second generation of stars after the Big Bang. In the first generation there must have existed a massive star, practically made of hydrogen alone, with about 30 times the mass of the sun. Such massive stars live a very short time, a few million years and then they explode as a supernova and with that material expelled in the supernova explosion, the star SDSS J0715-7334 was created about 13,000 million years ago.

In summary, SDSS J0715-7334 is the cleanest star known, a living fossil that brings us closer to understanding the first generations of stars in the cosmos, because after the birth of SDSS J0715-7334, with more supernova explosions, Kilonova and other cosmic events, the universe was filled with more and more heavy elements, more metals and with them the stars that were being born after SDSS were contaminated. J0715-7334.

Why is it so interesting? The star also helps us understand something intriguing, the limits of habitability of the universe, SDSS J0715-7334 is so pure and has so few metals and heavy elements that it is practically impossible for it to have planets like Earth, perhaps it has some planets, but they would be gaseous worlds of hydrogen and helium. SDSS J0715-7334 does not have heavy elements to form rocky planets, it does not have carbon, iron, heavy metals, calcium, or the rest of the typical elements that we would find on planets like Mars, Earth or Venus or Mercury.

This finding helps us understand that it took time for the universe to create enough material for planets like Earth to be born. Previous studies on the habitability of the universe come to the conclusion that between 12,000 to 11,000 million years ago there were already some stars with enough metallicity to form rocky planets like ours, but there was another problem at that time and that is that the universe was much more compact and also much more violent, there was a greater frequency of supernovae, gamma ray bursts, galactic collisions, stellar disturbances and black holes consuming everything that fell into them.

And that is not good for the creation of life, life needs certain elements, but it also needs tranquility to be able to evolve, which is why it is suspected that until about 3,000 million years ago after the Big Bang or approximately 11,000 to 10,000 million years ago, the universe was not calm enough for life to have a chance to flourish on the first rocky planets that were forming, billions of years, it seems like a long time, but in reality it is Very little if we compare it with the up to 100 billion years that it is estimated that stars will continue to shine in the universe, that is about 7,250 times the current age of the universe.

Then, when the last Red dwarf star goes out, stars that are smaller and cooler than the sun, but that can also live much longer, when the last star goes out, the stelliferous era will end, that is, the era of stars and also the era of life as we know it, it will be the beginning of the degenerate era.

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