Les astronomes viennent de découvrir une étoile si puissante qu'elle défie tout ce que nous savons sur la physique ! 🌟🚀 Ce géant cosmique émet une énergie au-delà de toute explication scientifique, laissant les experts complètement déconcertés. Comment produit-il autant de puissance ? 🤯 Certains pensent qu'il pourrait cacher un secret époustouflant—des mécaniques stellaires inconnues à quelque chose d'encore plus mystérieux. 🛸 Cela pourrait-il être la clé pour débloquer de nouvelles découvertes cosmiques qui réécrivent notre compréhension de l'univers ? Regardez maintenant et explorez l'étoile qui remet en question les lois mêmes de la science ! 🔥✨ Animation créée par Sympa.
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FunTranscript
00:00Look at this. Astronomers have recently discovered a neutron star, also called a dead star,
00:07spinning at an extraordinary speed of 716 rpm.
00:12It is one of the fastest stars we have ever found in the universe.
00:16And there is more than its speed.
00:18The surface of this neutron star is constantly erupting, with overpowering explosions.
00:23But before we dive into the mystery of this neutron star, let's see what these objects really are.
00:29They are formed from the remains of massive stars whose mass is at least eight times that of the Sun.
00:35When these stars run out of their nuclear fuel, they can no longer counter the force of gravity that attracts their matter inward.
00:43This leads to the collapse of their cores and triggers a gigantic supernova explosion,
00:49which shatters the outer layers of the star.
00:53What remains is an ultra-dense core, a neutron star.
00:57These stellar remains are incredibly small, usually only 19 km wide,
01:03and yet their mass is greater than that of the Sun.
01:07The density of neutron stars is also very impressive.
01:11Imagine that you take the mass of two suns and compress it into a sphere the size of a city.
01:16A single teaspoon of neutron star matter would weigh about 10 million tons.
01:21It is the equivalent of the combined weight of 85,000 blue whales.
01:25This extraordinary density is at the origin of the extremely powerful gravitational fields of neutron stars.
01:31When matter falls on a neutron star, it accelerates to a speed of several million kilometers per hour before hitting the surface.
01:39The energy released by such impacts is truly amazing.
01:42Despite its name, a neutron star does not only contain neutrons.
01:46Some protons also survive there.
01:48Normally, protons mutually repel each other because they present the same positive charge.
01:54But in a neutron star, the crushing gravity brings them so close together that the nuclear force takes over inexorably.
02:01It attracts them to the neutrons as if they were all part of the same team.
02:05Inside the star, the lower you go, the stranger things get.
02:09Near the surface, the neutrons agglutinate into amas, a bit like neutron gnocchi.
02:15A little lower, these amas assemble into long chains, forming what scientists call the spaghetti layer.
02:21I'm starting to get hungry.
02:23At even higher pressures, the spaghetti chains merge side by side, creating flat sheets, neutron lasagna.
02:30Continue to go down even deeper, and the lasagna ends up decomposing into a uniform mass.
02:36But even then, the structure is not smooth.
02:39There are spaces, long empty tubes that look a lot like breadcrumbs.
02:44Thus, inside a neutron star, you have layers of gnocchi, spaghetti, lasagna, and breadcrumbs.
02:51And each of these layers illustrates the breathtaking results of physics under immense pressure.
02:56Well, I'm definitely going to eat Italian today.
02:59This recently discovered neutron star is part of a binary system located in a mass of dense stars.
03:05This mass is located near the center of the Milky Way, about 26,000 light-years from Earth, towards the Sagittarius constellation.
03:13The record rotation speed of this star is extraordinary.
03:17If we take a period not of a second, but of a minute, we get more than 42,000 rotations.
03:23This new arrival is equal to another neutron star.
03:27They both rotate at exactly the same speed.
03:30Such extreme rotation speeds are rare, and make these stars special in terms of behavior and property.
03:37But that's not all. We can't help but mention the binary partner of our neutron star.
03:43It is a white dwarf, the dense vestige of a star similar to our sun in terms of size.
03:49This white dwarf is also very fast.
03:52It orbits around the neutron star every 11 minutes.
03:55This makes the couple a binary system with the shortest orbital period ever observed.
04:00Imagine a stellar object spinning around its partner faster than it takes to prepare a cup of coffee.
04:06Yes, that's the kind of speed we're talking about here.
04:10This tight and fast orbit shows us how powerful the gravitational forces are inside the system.
04:17You may be wondering why neutron stars spin so fast.
04:21It's a matter of conservation of the kinetic moment.
04:24Let me explain.
04:25When a massive star collapses to become a neutron star, it shrinks considerably.
04:30Such a fast compression instantly accelerates its rotation.
04:34It's like a skater who spins faster when he puts his arms in.
04:37And the smaller the star is, the faster it spins, which leads to extreme rotation speeds.
04:44In binary systems like this one, neutron stars can reach even higher rotational speeds.
04:51Their trick is to steal matter from their companion stars.
04:55This process is called shuffling.
04:58No, I'm kidding.
04:59It's called accretion.
05:00The stolen matter carries a kinetic moment that increases the rotation speed of the neutron star.
05:05This matter can also accumulate at the surface of the neutron star,
05:09which ends up triggering powerful thermonuclear explosions.
05:12It releases an immense amount of energy,
05:15temporarily giving the star a luminosity up to 100,000 times that of the Sun.
05:20This allows astronomers to study the complex details of these extreme environments.
05:25The X-ray instrument of NASA aboard the International Space Station,
05:29officially called Neutron Star Interior Composition Explorer,
05:34and fortunately nicknamed NESER,
05:37observed 15 thermonuclear explosions at the surface of our neutron star between 2017 and 2021.
05:43One of these explosions revealed a unique pattern called thermonuclear oscillations,
05:49which are very asymmetrical luminosity spots on the burning surface layers of neutron stars in accretion.
05:55This pattern corresponded to the star's rotational speed,
05:59and thus confirmed its extreme speed.
06:01But wait, the best is yet to come.
06:04If neutron stars are already extreme,
06:07there is another category that raises the level of a notch.
06:10Magnetars.
06:12Magnetars are neutron stars with incredibly powerful magnetic fields,
06:17up to a billion times more powerful than the Earth's magnetic field.
06:21These fields distinguish them from other neutron stars.
06:25They can deform the atoms of nearby objects, making life impossible up close.
06:30As for the energy density of a magnetar's magnetic field, it is extremely high,
06:3510,000 times higher than the mass density of lead.
06:39Magnetars also produce X-ray and gamma-ray surges so powerful
06:44that they can temporarily eclipse entire galaxies.
06:47These surges are often triggered by stellar eclipses,
06:50violent displacements of the magnetar's crust caused by its own magnetic fields.
06:55For example, in 2004, a gamma-ray surge from a magnetar was so powerful
07:00that it disturbed the Earth's ionosphere.
07:02It hit the Earth, and it was so intense that several satellites were able to detect it.
07:07The Swift satellite, built specifically to detect the universe's gamma-ray surges,
07:12not only recorded the explosion,
07:14it was hit by such energy that its sensors were completely overloaded.
07:18And Swift was not even in front of the surge.
07:21The energy was so strong that it crossed the spacecraft and submerged its cameras.
07:26If a magnetar was as close to the Earth as the Moon,
07:29its magnetic field would delete all credit card data on the planet by erasing the magnetic bands.
07:35This is the level of power we have to deal with here.
07:39Magnetars are extremely active, but for a relatively short time.
07:43Their intense magnetic field weakens after about 10,000 years.
07:47After that, they stop emitting powerful X-ray and gamma rays.
07:51Astronomers think that there are at least 30 million inactive magnetars in the Milky Way alone.
07:57These silent cosmic remains are scattered throughout the galaxy.
08:01Neutron stars and magnetars serve as laboratories for extreme physics.
08:06They allow astronomers to better understand the behavior of certain materials
08:10in conditions that you could never reproduce on Earth.
08:14The incredible density of these objects helps scientists to understand what happens
08:19when protons and electrons are compressed together to form neutrons.
08:23This creates states of matter that do not exist anywhere else in the universe.
08:28These violent explosions on neutron stars and magnetars
08:32also play an essential role in the formation of heavy elements such as gold and platinum.
08:38These elements are dispersed throughout the universe during these energetic events
08:42to finally become part of the planets and stars, and of you and me.
08:46In fact, NASA's NICER instrument played a key role in discovering the mystery of neutron stars.
08:53Its ability to detect X-rays with great precision
08:57allowed astronomers to study the fast rotation of the star we talked about
09:01as well as the thermonuclear explosions that occur on its surface.
09:06Really breathtaking.