A star is merely a thermonuclear explosion in very, very slow motion. But it is towards the end of their lives that stars reach an almost always impressive maturity, and some a more than spectacular death, releasing billions of tons of matter in a swan song that reaches the ends of the Universe. A star like ours burns hydrogen in the nucleus and converts it into helium, which, heavier than the hydrogen in the rest of the nucleus, accumulates in the center.
When the percentage of hydrogen in the nucleus drops below a certain concentration, the star is poisoned by helium (it is actually a term astronomers use) and with no hydrogen left to use as fuel, it begins to compress under weight. of its outer layers. From here, things get trickier, and this is where the true red giant begins! For example, the nearest red giant star to our System, Gamma Crucis, Gacrux (which literally means Southern Cross, like the constellation that calls it and of which it is the third brightest). Although it is only 30% more massive than the Sun, it has grown to more than 80 times its radius. Or Alpha Tauri, Aldebaran, the brightest star in the constellation of the Bull, thirteenth in brightness in the firmament and the first red giant that always comes to mind. Aldebaran does not even have two solar masses by far, but it is 420 times larger than the star we see every day (though not very bright orange, it must be said).
Our Sun, being a main-sequence star of a certain mass, is assured of a future as a red giant, at last. Many measurements have been made by various teams of solar physicists – specialists in the Sun – who today agree that in about 5 or 6 billion years the star will see most of its hydrogen consumed to burn, and will begin to become a full-fledged red giant. With a bit of calm, as the process is estimated to take about 500 or 600 million years, which is also not long in astronomical terms; by the time this happens, the Sun’s mass will have increased to about 260 times its current size, and it will be more than 2,600 times more light. Of course, our planet and everything it inhabits at that time will be consumed in what will be part of the Sun’s corona, Venus and Mercury will go with us. Nothing stands in the way of a star.
From here, a red giant has two paths each, depending on its mass, and the critical number here is 2.5 solar masses. For the Sun, once the hydrogen fusion phase is complete, it will begin firing enormous amounts of matter into the universe in the form of pulsations. Until it cools and shrinks enough to become a white dwarf. However, a more massive star has a longer and brighter future depending on its size; red giants have a limit of 8-9 solar masses according to the most recent consensus. A star of this size will go through a process of billions of years in which it will change its size several times, gradually expanding and compressing, until it ignites the helium that results from the fusion of hydrogen, which acts as fuel. will serve for at least a billion years to continue to enjoy its status as a red giant, getting bigger and bigger until its outer layer leaves it due to a mere lack of gravity, which is a super-dense metal core the size leaving behind the Earth, which floats in the Universe and cools itself, forever.
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He is a computer systems engineer. His areas of knowledge are technologies, science and the environment.
Reference-www.eleconomista.com.mx