Voici Ce Qui Rend Le Centre De La Voie Lactée Si Lumineux

Sympa

Le centre de la Voie lactée est super brillant parce qu'il est rempli de nombreuses étoiles et d'un trou noir supermassif. Ce trou noir, appelé Sagittarius A*, est des millions de fois plus grand que notre soleil ! Il attire du gaz, de la poussière et même des étoiles, et à mesure qu'ils s'approchent, ils chauffent et brillent, rendant la zone vraiment lumineuse. Il y a aussi un énorme nuage de gaz chaud et des tonnes d'étoiles entassées, ce qui ajoute à la lueur. Certaines étoiles explosent en supernovas, qui sont aussi extrêmement lumineuses. Plongez pour explorer cela et d'autres faits intéressants sur l'espace.  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

Transcript

00:00Is there a gigantic mega sun in the center of our Milky Way?

00:04Scientists have actually believed that for a while, because it is the brightest region of the galaxy.

00:10It contains millions of stars concentrated in a restricted area called the galactic bulb.

00:17The galactic bulb contains a density of stars per light year much higher than that of any other part of the galaxy.

00:24It can be up to 10 million times denser than our sector.

00:27Sometimes, the stars are separated by only 5 light days,

00:31which would correspond to the presence of another star in our solar system,

00:35just beyond Pluto at the spatial scale.

00:38But what explains such a density?

00:41During the formation of galaxies, large amounts of gas and dust

00:45come together under the influence of gravity.

00:48These materials accumulate and eventually form stars.

00:52Gravity and the kinetic moment find a balance,

00:55giving rise to a flat disk structure with a dense and luminous core,

00:59often presenting a bulging shape.

01:01The stars continue their quiet existence,

01:04and when they reach the end of their life cycle,

01:06they collapse under their own weight,

01:08which leads to the formation of a black hole.

01:11Black holes are greedy for everything that surrounds them,

01:14and the more they absorb matter, the more they grow.

01:17And what better place for a cosmic feast than the center of the galaxy,

01:21where matter is gathered in abundance.

01:23When the black hole begins to absorb gas and surrounding dust,

01:27it forms an accretion disk.

01:29As this matter spirals towards the black hole,

01:32it heats up and releases a large amount of energy,

01:35thus making the center of the galaxy even brighter.

01:38This is why we find both supermassive black holes

01:42and galactic bulbs in the center of all galaxies.

01:46The galactic bulb located in the center of the Milky Way

01:49has a slightly elliptical shape.

01:51It is what is called a classic bulb.

01:53The stars in this region differ from our sun.

01:56They move randomly in all directions and all possible planes,

02:01and each has a different speed.

02:03Gravity is therefore chaotic there,

02:05which gives the bulbs an appearance close to a sphere or an ellipse.

02:09Being the first to form,

02:11these areas house some of the oldest stars in our galaxy.

02:15However, there are also stellar formation regions,

02:19populated by young massive stars,

02:21aged less than 100 million years.

02:23As we move away from the center,

02:25the environment becomes more peaceful.

02:28The stars begin to rotate regularly and stabilize.

02:32Currently, the Earth is in one of the spiral arms of the Milky Way,

02:37called the Orion arm,

02:39located at a great distance from the galactic bulb.

02:42In our neighborhood,

02:43the stars are generally separated by 4 or 5 light years.

02:47This implies that most of a galaxy

02:49is actually made up of a black and empty space.

02:53Our black hole is called Sagittarius.

02:56It is huge,

02:58with a mass about 4 million times that of our sun.

03:02Its size is also about 51 million kilometers in diameter,

03:06which is comparable to the distance between Mercury and the sun.

03:10But do not worry,

03:12it does not threaten to swallow the Milky Way or absorb us.

03:15These black holes are actually very small compared to the whole galaxy

03:20and can only consume what is nearby.

03:23Currently, many stars orbit around Sagittarius A.*.

03:28Although it emits a huge amount of energy,

03:31its light is difficult to observe from Earth

03:34without a significant scientific effort.

03:36But why don't we see the center of our own galaxy?

03:40The galactic bulb is so bright

03:42that at 26,000 light years away,

03:44we should see it shine intensely in our sky.

03:48And yet, this is not the case.

03:50The reason is interstellar dust.

03:53There is a large amount of dust between us and the galactic nucleus,

03:57which absorbs most of the visible light.

03:59We can only observe the galactic nucleus

04:02by using other types of light,

04:04such as near infrared or gamma rays.

04:08NASA has images of the nucleus taken in different types of light,

04:12showing how extremely bright the center is

04:15without the dust that obstructs our view.

04:17However, all luminous regions are not hidden by gas and dust.

04:21For example, when we observe dense clusters like Messier 13,

04:25the stars are so close to each other

04:28that they appear like a simple white spot.

04:30Most telescopes cannot distinguish them.

04:33The M32 satellite galaxy,

04:35our neighbor near the Andromeda galaxy,

04:37contains about 84 stars per light year.

04:40Its density is such that even the Hubble Space Telescope

04:43cannot process the stars individually.

04:46To get an idea,

04:47our solar system measures about two light years long.

04:51If we were there,

04:52we could see about 168 stars through the window.

04:56The closest stellar system to us is Alpha Centauri,

04:59located about four light years from the Sun.

05:02If it was only a few light days away,

05:04it would shine much more intensely than the full moon.

05:07Thus, if we managed to survive in extremely dense star regions,

05:12the sky would be completely white all day.

05:15But it is unlikely to be achievable.

05:18As we get closer to the center of the Milky Way,

05:21the chances of finding life become extremely low.

05:24The gravity of the stars is extreme,

05:26with unpredictable movements,

05:28leaving little room for other objects.

05:31On these rare planets,

05:32the radiation of cosmic rays is incredibly high.

05:35Supernova explosions and star collisions nearby become frequent,

05:40and the surrounding gas makes it almost impossible to breathe,

05:43or even have a clear vision.

05:45On the other hand,

05:46as we move away,

05:47the number of stars decreases.

05:49The essential elements of life,

05:50such as carbon,

05:51oxygen,

05:52and iron,

05:53produced by the stars,

05:54also become less numerous.

05:56Too much radiation is harmful,

05:57but too little radiation means

05:59that there is not enough energy to support crucial chemical reactions,

06:03such as photosynthesis.

06:05This is why,

06:06if extraterrestrial life exists,

06:07it would probably be somewhere in the more central regions of galaxies.

06:11But some galaxies must have their sparkle at an active galactic nucleus.

06:15These are extremely energetic regions,

06:18located in the center of certain galaxies.

06:21They shine much more intensely than any imaginable star.

06:25However,

06:26their luminosity manifests itself mainly

06:28in certain parts of the electromagnetic spectrum.

06:31This luminosity does not come from stars,

06:33but from the accretion disk surrounding their supermassive black holes.

06:37As matter slowly falls into a black hole,

06:40it accumulates around it,

06:42and forms a flat disk

06:44of gas,

06:45dust,

06:46and other rotating elements.

06:48Due to the extreme conditions of gravity and friction,

06:51this disk heats up

06:53and begins to emit enormous amounts of energy.

06:56In addition,

06:57this disk rotates at a speed almost equal to that of light.

07:00As a result,

07:01collisions occur constantly

07:03and are of unimaginable power,

07:05releasing even more energy.

07:07Most galaxies do not have an active galactic nucleus,

07:11or Enneag.

07:13Those that do,

07:14like the M87 galaxy in the constellation of the Virgin,

07:17are called active galaxies.

07:19There are also different types of Enneag,

07:22such as the Seyfert galaxies,

07:24the Radio galaxies,

07:26and finally the Quasars,

07:28which are the champions in terms of spatial luminosity.

07:31Imagine objects so brilliant

07:33that they can surpass the luminosity of the entire galaxy to which they belong.

07:37Quasars are a particular type of active galactic nucleus,

07:41the most extreme and brightest form.

07:44They are associated with supermassive black holes,

07:47the largest in our universe.

07:49Quasars are like a combination of several phenomena.

07:52First of all,

07:53they are the brightest accretion disks that can be observed.

07:56Thanks to their huge black holes,

07:58which absorb everything that surrounds them,

08:00they also have remarkable characteristics.

08:03Powerful particles jets

08:05that burst from the black hole's shoulder

08:07at speeds close to that of light.

08:09These jets increase the luminosity of the Quasar,

08:12although they can only be detected in the form of radio waves.

08:15The energy they emit is such

08:17that they can be observed for billions of light years.

08:20However,

08:21the closest Quasar is located at 600 million light years,

08:25which makes its observation impossible with amateur telescopes.

08:29Thus,

08:30when we observe a galaxy through a telescope,

08:33we usually only see the brightest nucleus,

08:36neglecting the external parts.

08:38Alas,

08:39our eyes are simply not made to perceive objects

08:42like galactic active nuclei.

08:44This is why these stars are among the brightest we can see.

08:48But what a stunning spectacle!

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