The Last Star in the Universe – Red Dwarfs Explained Der letzte Stern im Universum - Rote Zwerge erklärt Το τελευταίο αστέρι στο σύμπαν - Εξηγήσεις για τους κόκκινους νάνους La última estrella del Universo - Explicación de las enanas rojas La dernière étoile de l'univers - Les naines rouges expliquées 宇宙最後の星、赤色矮星を解明する 우주의 마지막 별 - 적색 왜성 설명 De laatste ster in het heelal - Rode dwergen uitgelegd Ostatnia gwiazda we Wszechświecie - czerwone karły wyjaśnione A última estrela do universo - Anãs vermelhas explicadas Последняя звезда во Вселенной - объяснение красных карликов Evrendeki Son Yıldız - Kırmızı Cüceler Açıklandı Остання зірка у Всесвіті - червоні карлики: пояснення 宇宙中最后一颗恒星——红矮星的解释 宇宙中的最后一颗恒星--红矮星解析

One day the last star will die and the universe will turn dark forever. Un jour, la dernière étoile mourra et l'univers s'obscurcira à jamais.

It will probably be a red dwarf; a tiny kind of star. Il s'agira probablement d'une naine rouge, un type d'étoile minuscule.

That's also one of our best bets to find alien life, and might be the last home of humanity before the universe becomes uninhabitable. C'est aussi l'une des meilleures chances de trouver de la vie extraterrestre, et peut-être le dernier foyer de l'humanité avant que l'univers ne devienne inhabitable.

So, what do we know about them, and why are they our last hope?

At least 70% of stars in the universe are red dwarfs. Au moins 70 % des étoiles de l'univers sont des naines rouges.

They are the tiniest stars out there, with only about 7 to 50% of the mass of our sun. Ce sont les plus petites étoiles qui existent, avec seulement 7 à 50 % de la masse de notre soleil.

Not that much bigger than our planet Jupiter, which is still huge though.

They are also very dim. Elles sont également très peu lumineuses. Eles também são muito escuros.

It is impossible to see them with the naked eye.

You have never seen one in the night sky.

Even with all our technology, we can only clearly observe red dwarfs in our neighborhood.

Approximately 20 of the 30 stars close to earth are red dwarfs.

Like all stars, red dwarfs fuse hydrogen into helium. Como todas as estrelas, as anãs vermelhas fundem hidrogênio em hélio.

But while more massive stars accumulate all the fused helium in their cores, Mais les étoiles plus massives accumulent tout l'hélium fondu dans leur cœur, Mas enquanto estrelas mais massivas acumulam todo o hélio fundido em seus núcleos,

red dwarfs stay convective, meaning that the helium and hydrogen constantly mix. Les naines rouges restent convectives, ce qui signifie que l'hélium et l'hydrogène se mélangent en permanence. as anãs vermelhas permanecem convectivas, o que significa que o hélio e o hidrogênio se misturam constantemente. So they use up their fuel incredibly slowly, before they are extinguished. Así que consumen su combustible increíblemente despacio, antes de extinguirse. Ils consomment donc leur carburant incroyablement lentement, avant de s'éteindre. Então eles consomem seu combustível incrivelmente devagar, antes de serem extintos.

Red dwarfs burn so slowly, that their average lifespan is between 1 and 10 trillion years Les naines rouges brûlent si lentement que leur durée de vie moyenne se situe entre 1 et 10 billions d'années. As anãs vermelhas queimam tão lentamente que sua vida útil média é entre 1 e 10 trilhões de anos

by comparison, the Sun will survive for another 5 billion years

Because the universe is only 13.75 billion years old

not a single red dwarf has reached the later development stages ni una sola enana roja ha alcanzado las últimas fases de desarrollo aucune naine rouge n'a atteint les derniers stades de développement nem uma única anã vermelha atingiu os estágios posteriores de desenvolvimento

Every single one of the trillions that exist is still a baby. Cada uno de los billones que existen sigue siendo un bebé. Chacun des billions d'individus qui existent est encore un bébé.

Speaking of babies, the smallest star in the entire Hablando de bebés, la estrella más pequeña de toda la

universe is also a red dwarf because small red dwarfs are right on the verge of being a star at all. universo es también una enana roja porque las enanas rojas pequeñas están justo al borde de ser una estrella en absoluto. est également une naine rouge, car les petites naines rouges sont à la limite de l'étoile. universo também é uma anã vermelha porque pequenas anãs vermelhas estão à beira de ser uma estrela.

Just a tiny bit less hydrogen and they are mere brown dwarfs: failed stars Un tout petit peu moins d'hydrogène et ce sont de simples naines brunes : des étoiles ratées. Apenas um pouquinho menos de hidrogênio e elas são meras anãs marrons: estrelas fracassadas

that cannot sustain a fusion reaction for long. que não pode sustentar uma reação de fusão por muito tempo.

So what about aliens or a new home for Humanity?

Since our Sun will die one day, we'll eventually need to look for

a new home and where there are habitable planets, there might also be aliens. Un nouveau foyer et là où il y a des planètes habitables, il peut aussi y avoir des extraterrestres. um novo lar e onde há planetas habitáveis, também pode haver alienígenas.

The Kepler space observatory found that at least half of all red dwarfs host rock L'observatoire spatial Kepler a découvert qu'au moins la moitié des naines rouges abritent des roches. O observatório espacial Kepler descobriu que pelo menos metade de todas as anãs vermelhas hospedam rochas

planets between half and four times the mass of our Earth. des planètes dont la masse est comprise entre la moitié et le quadruple de celle de notre Terre.

Many of them are in the habitable zone -- the area around a star where water can be liquid -- Nombre d'entre elles se trouvent dans la zone habitable, c'est-à-dire la zone autour d'une étoile où l'eau peut se trouver à l'état liquide.

but since red dwarfs burn at relatively cold temperatures, a planet would need to

be really close to be hospitable, probably as close as Mercury to our Sun

or even closer, which brings with it all kinds of problems. For example, a planet

this close to a star would probably be tidaly locked, meaning the same side tan cerca de una estrella probablemente estaría bloqueado por mareas, lo que significa que el mismo lado si proche d'une étoile serait probablement verrouillé par la marée, ce qui signifie que le même côté serait verrouillé par la marée. tão perto de uma estrela provavelmente seria bloqueado por maré, significando o mesmo lado

would always face it. This side would be incredibly hot while the shadow side estaría siempre de cara. Este lado estaría increíblemente caliente mientras que el lado de la sombra

would be frozen, which makes it hard for life to develop. se congelaría, lo que dificulta el desarrollo de la vida.

Although a planet with a big enough ocean might be able to distribute the star's energy and create some kind of stability. Aunque un planeta con un océano lo suficientemente grande podría ser capaz de distribuir la energía de la estrella y crear algún tipo de estabilidad. Toutefois, une planète dotée d'un océan suffisamment grand pourrait être en mesure de répartir l'énergie de l'étoile et de créer une certaine stabilité.

All the gravitation forces of a Red Dwarf could squeeze the planet and heat it up so much Todas las fuerzas gravitatorias de una Enana Roja podrían apretar el planeta y calentarlo tanto Toutes les forces de gravitation d'une naine rouge pourraient comprimer la planète et la réchauffer à un tel point Todas as forças gravitacionais de uma anã vermelha podem apertar o planeta e aquecê-lo tanto

that it might loose all its water over time. que podría perder toda su agua con el tiempo. que pode perder toda a sua água ao longo do tempo.

These planets could end up like Venus, a hot burning hell.

Another problem is that, many Red Dwarfs vary in their energy output Outro problema é que muitas anãs vermelhas variam em sua produção de energia

They could be covered in star spots that can dim their emitted light by up to 40% for months Podrían estar cubiertas de manchas estelares capaces de atenuar su luz emitida hasta un 40% durante meses Elles pourraient être couvertes de taches d'étoiles qui peuvent réduire leur lumière émise jusqu'à 40 % pendant des mois. Eles podem ser cobertos por manchas estelares que podem diminuir a luz emitida em até 40% por meses

Wich would cause oceans on planets to freeze over. Wich provocaría la congelación de los océanos de los planetas.

At other times, they can emit powerful solar flares; sudden outbursts of energy incredibly powerful. En otras ocasiones, pueden emitir potentes llamaradas solares; repentinos estallidos de energía increíblemente poderosos. Outras vezes, podem emitir poderosas erupções solares; explosões repentinas de energia incrivelmente poderosas.

These Red Dwarfs could double their brightness in minutes

Wich could strip away sizable portions of a planet's atmosphere and burn it, rendering its Wich podría arrancar partes considerables de la atmósfera de un planeta y quemarlo, haciendo que su Wich pourrait arracher des parties importantes de l'atmosphère d'une planète et la brûler, ce qui rendrait sa vie plus difficile. Que poderia arrancar porções consideráveis da atmosfera de um planeta e queimá-lo, tornando sua

On the other hand, their extremely long life span is a big plus. Por otro lado, su larguísima vida útil es una gran ventaja. Por outro lado, sua vida útil extremamente longa é uma grande vantagem.

A Red Dwarf with just moderate levels of activity, could be an amazing place for a planet that hosts life. Una Enana Roja con niveles moderados de actividad podría ser un lugar asombroso para un planeta que albergara vida. Une naine rouge avec un niveau d'activité modéré pourrait être un endroit étonnant pour une planète abritant la vie. Uma anã vermelha com níveis moderados de atividade pode ser um lugar incrível para um planeta que abriga vida.

Life on Earth has existed for about 4 Billion years

And, we have about a Billion years left before the sun becomes so hot, that complex life on Earth

will become impossible.

We will either die out or leave Earth and look for a new home.

We could build a civilization for potentially trillions of years, around a Red Dwarf with the right conditions. Nous pourrions construire une civilisation pendant des billions d'années autour d'une naine rouge si les conditions étaient réunies.

About 5% of the Red Dwarf in the Milky Way, may host habitable, roughly Earth sized planets. Environ 5 % des naines rouges de la Voie lactée pourraient abriter des planètes habitables, de la taille de la Terre.

That would be more than 4 Billion in total.

But, life may not even need a planet like Earth.

Candidates for life around a Red Dwarf may be the moons of Gas Giants, also called Super Earths Les candidats à la vie autour d'une naine rouge pourraient être les lunes des géantes gazeuses, également appelées "super-terres". Candidatos à vida em torno de uma anã vermelha podem ser as luas de gigantes gasosos, também chamadas de superterras

Really massive rocky planets. Planetas rochosos realmente maciços.

All alone, there are an estimated 60 Billion potentially habitable planets around Red Dwarfs. Por si só, existem cerca de 60 bilhões de planetas potencialmente habitáveis em torno das anãs vermelhas.

And, that's in the Milky Way alone.

So, Red Dwarfs might become really important for our survival in the future

But, everything has to die at some point, even Red Dwarfs.

When in Trillions of years, the life of the last Red Dwarf is about to end, it will not be a very spectacular event.

As its hydrogen runs out, it shrinks, becoming a Blue Dwarf, burning out completely. À medida que seu hidrogênio se esgota, ele encolhe, tornando-se uma anã azul, queimando completamente.

After its fuel is spent, it's transformed into a White Dwarf, an object about as small as Earth

Packed very densely and made of degenerate gasses, mostly of Helium-4 nuclei. Très dense et composé de gaz dégénérés, principalement de noyaux d'hélium 4. Embalado muito densamente e feito de gases degenerados, principalmente de núcleos de hélio-4.

Having no more source of energy, it will cool extremely slowly over trillions of years. N'ayant plus de source d'énergie, il se refroidira extrêmement lentement pendant des billions d'années.

Until it becomes its final form: A cold Black Dwarf.

White and Black Dwarfs are so fascinating, that they deserve their own video.

Anyway.. It's going to be a long time before the last in the Universe vanish De qualquer forma .. Vai demorar muito até que o último do Universo desapareça

It's kind of uplifting to know that, if humanity succeeds in venturing into Space Il est réconfortant de savoir que, si l'humanité réussit à s'aventurer dans l'espace, il sera possible d'en tirer profit. É meio animador saber que, se a humanidade conseguir se aventurar no Espaço

We have plenty of time, before the Universe turns out the lights. Temos muito tempo, antes que o Universo apague as luzes.

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