Préparez-vous pour une histoire d'horreur cosmique : des étoiles zombies qui refusent de mourir et qui se dévorent vivantes ! Dans l'espace profond, certaines étoiles explosent dans une déflagration appelée supernova, mais au lieu de disparaître, ces étoiles « zombies » reviennent sans cesse. Elles attirent l'énergie et la matière d'une étoile voisine, s'en nourrissant comme un vampire de l'espace, jusqu'à ce qu'elles soient suffisamment puissantes pour exploser à nouveau ! À chaque explosion et résurrection, elles deviennent plus affamées, attirant de plus en plus de matière de leur compagnon dans une danse étrange et mortelle. Les astronomes sont fascinés par ces étoiles mortes-vivantes, observant le cannibalisme cosmique se dérouler. C'est une vision sauvage et envoûtante, prouvant que même les étoiles peuvent avoir une vie après la mort ! Animation créée par Sympa. ---------------------------------------------------------------------------------------- Musique par Epidemic Sound https://www.epidemicsound.com Pour ne rien perdre de Sympa, abonnez-vous!: https://goo.gl/6E4Xna ---------------------------------------------------------------------------------------- Nos réseaux sociaux : Facebook: https://www.facebook.com/sympasympacom/ Instagram: https://www.instagram.com/sympa.officiel/ Stock de fichiers (photos, vidéos et autres): https://www.depositphotos.com https://www.shutterstock.com https://www.eastnews.ru ---------------------------------------------------------------------------------------- Si tu en veux encore plus, fais un tour ici: http://sympa-sympa.com
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00:00Passionate astronomers, come closer, because great news is waiting for you.
00:04Researchers have recently completed the complete cartography of two pairs of stars located beyond our galaxy, the Milky Way, which literally devours their stellar neighbors.
00:14This progress not only enriches our understanding of the stars, but also offers new perspectives to measure the distances in the immensity of the night sky.
00:23Did you know that more than half of the stars in our Milky Way existed in binomial?
00:29Although it is likely that other galaxies also house many binary stars, their low luminosity generally makes them invisible.
00:38However, the so-called symbiotic stars, where one star absorbs the other, are distinguished by their exceptional brilliance, which facilitates their study.
00:48Scientists believe that the analysis of the orbits of these systems is a crucial step in understanding whether other galaxies produce binary stars comparable to those of the Milky Way.
01:00Now let's get into the details.
01:02Although a pair of stars can be born simultaneously, their evolution differs depending on their respective mass.
01:08The most massive star consumes its fuel faster, reaching rather the end of its life cycle to become a compact white dwarf.
01:17These white dwarfs, although small and not very bright, concentrate a mass equivalent to that of the Sun in a volume comparable to that of the Earth.
01:26If they are close enough to their companion, their gravity can capture the matter, thus producing a signal that can be detected at great distances.
01:34The recently mapped symbiotic star systems are called Draco C1 and LIN 358.
01:42The stars of Draco C1 take about three terrestrial years to complete an orbit around each other, while that of LIN 358 takes a little more than two years.
01:53These are the first complete orbital measurements made on symbiotic systems beyond the Milky Way.
01:59This new data will provide astronomers with the keys to better understand the formation of stars in other galaxies.
02:07In some symbiotic systems, a white dwarf can accumulate enough matter from its companion to explode into a supernova.
02:15The latter, of spectacular luminous intensity, are visible throughout the universe.
02:21As they all reach an initial luminosity identical to that of a nearby observer, they serve as standard candles to measure cosmic distances.
02:30Although Draco C1 and LIN 358 are unlikely to know of such an explosion in the near future, their study contributes to enlighten the mechanisms of evolution of these stellar references.
02:42If you want to deepen your knowledge of the strangest stars, rest assured, we are not done yet.
02:49Have you ever wondered about the most gigantic stars in the universe?
02:54Scientists have recently identified a colossal star named Uyghur Scuti.
03:00Located at about 9,500 light-years from Earth, it exceeds all common measure.
03:06It is about 1,700 times larger than our sun, which means that if it were in our solar system, it would extend well beyond the orbit of Jupiter.
03:16But that's not all. Uyghur Scuti is not only immense, it is also spectacularly luminous.
03:24Classified as a super red giant by scientists, this star shines with an intensity of about 340,000 times that of our star.
03:33However, if you imagine taking advantage of its rays to tan, forget this idea. It is far too far for that.
03:42You may be wondering how such a star, Q-Uyghur Scuti, was formed.
03:47Like any other star, everything begins with a cloud of gas and dust that collapses under the effect of its own gravity, generating a growing heat.
03:56When the temperature at the heart of the cloud reaches a critical threshold, the nuclear fusion starts and a star is born.
04:04But Uyghur Scuti continued to grow, absorbing more and more gas and dust to become a real colossus.
04:12This process continued until it reached the dimensions we know today.
04:17Although fascinating, Uyghur Scuti is not the only giant star in the universe.
04:22Others, such as Vihui Canis Majoris, have also caught the attention of scientists.
04:28Vihui Canis Majoris, formerly considered the largest star before Uyghur Scuti, remains nevertheless impressive.
04:37With a diameter of about 1,400 times that of our sun, it is located about 5,000 light years from our planet.
04:46But here is the most impressive.
04:48Stars like Uyghur Scuti and Vihui Canis Majoris are not even the largest structures in the universe, far from it.
04:55There are objects called hypergiants that make these insignificant stars appear.
05:00Among them is Stephenson 2-18, located about 21,000 light years away.
05:06With a size almost 2,150 times higher than that of our sun, it shines with a luminosity equivalent to that of 7 million of them.
05:15And if it already seems extravagant to you, know that a mysterious object, nicknamed the Great Attractor,
05:21exerts a gravitational force on the entire local group of galaxies, irresistibly attracting them.
05:27The nature and cause of this phenomenon remain unknown.
05:30But a hypothesis evokes the presence of a gigantic hypergiant cluster.
05:35Faced with such an entity, we would be absolutely tiny.
05:39Now let's move on to a star of the most original, practically out of a heavy metal concert.
05:45Joking aside, scientists have discovered a star called Sunen in heavy metal, an exceptionally rich metal star.
05:53This star contains more metal in its composition than any other star observed to date.
05:59Elements such as iron, nickel and chrome abound there, with an iron content about 10,000 times higher than that of our sun.
06:08For this discovery, astronomers used spectroscopy,
06:12which consists of analyzing the light emitted by the star in order to identify the constitutive elements.
06:18By examining the luminous spectrum, scientists have highlighted an abnormally rich metal composition,
06:25which distinguishes this star from all the others.
06:28And that's not all. This Sunen in heavy metal is not distinguished only by its metal richness.
06:34It has other amazing characteristics.
06:37Not only is it smaller and colder than our sun, but it is also remarkably ancient.
06:44It dates back almost to the beginning of the universe.
06:47What does all this mean?
06:49Scientists hope that by analyzing this Sunen in heavy metal,
06:54they will be able to deepen their knowledge of the primitive universe.
06:59Since this star dates back to the time when the universe began to form,
07:03it has witnessed major events.
07:06The study of its composition and properties could offer valuable clues about the appearance and conditions of the universe at its origins.
07:15The next star on the list is truly captivating.
07:18It is Vega, one of the brightest stars in the night sky.
07:23Many recognize it as this bright, sparkling point in the constellation of Lyra.
07:28And the most impressive, it is only about 25 light-years away from us,
07:33which, at the scale of the universe, is practically the door next door.
07:37Scientists have been studying Vega for decades and have made fascinating discoveries.
07:43For example, Vega is a relatively young star, only a few hundred million years old.
07:49It may seem long, but compared to the 4.6 billion years of our sun, Vega is a newborn.
07:56In addition to being young, Vega is extremely hot, with a surface temperature nearing 9,400 ° C.
08:04To put this into perspective, the surface of our sun reaches about 5,500 ° C.
08:10So, if you find terrestrial heat difficult to bear, imagine what a day on Vega would be like.
08:18Another interesting thing about this star is that it is surrounded by a dust and gas disk,
08:24called a debris disk.
08:26This disk is made up of remains of material from the formation of the star.
08:31Scientists believe that this disk is comparable to the one that surrounded our solar system in its early days.
08:38Vega is also a source of cosmic rays.
08:41These rays are high-energy particles that travel through space at phenomenal speeds.
08:46They are composed of protons, electrons and other particles,
08:50but their exact origin remains a mystery to scientists.
08:54However, they know that Vega is one of the places where these cosmic rays come from.
08:59But that's not all.
09:01Vega is also an emblematic star in popular culture.
09:04It appears in many works as a source of inspiration,
09:07mainly thanks to its luminosity and its fascinating characteristics.