Red Dwarves in Space
Red Dwarves: The Giant Tortoises of Space
by Vineet Karlepalem . Class 7, Vidyashilp, Bangalore
A red dwarf is a tiny kind of star which is one of our best bets to find alien life, and might be the last home of Humanity before the universe becomes uninhabitable.At least 70% of stars in the universe are red dwarfs. They are the tiniest stars out there, with only about 7% to 50% of the mass of our sun, roughly the same size as Jupiter, the largest planet of our solar system. They are also very dim. It’s impossible to see them with the naked eye. Even with all our technology, we can only clearly observe red dwarfs in our space neighborhood, the Local Group.
Approximately 20 of the 30 stars close to Earth are red dwarfs. Like all stars, red dwarfs fuse hydrogen into helium, but while more massive stars accumulate all the fused helium in their cores, red dwarfs stay convective, meaning that the helium and hydrogen constantly mix, so they use up their fuel incredibly slowly before they are extinguished. Red dwarfs burn so slowlythat their average lifespan is between one and ten trillion years;by comparison, the Sun will survive for only another five billion years. Because the universe is only 13.75 billion years old, every single one of the trillions that exist is still a baby.
Speaking of babies, the youngest star in the entire universe is also a red dwarf because small red dwarfs are right on the verge of being a star at all.
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. The Kepler Space Observatory found that at least half of all red dwarfs host rocky planets around the same mass of our Earth. Many of them are in the habitable zone, the area around a star where water can be liquid, 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. But, a planet this close to its star will bring it deal-breaking problems. For example, a planet this close to a star would probably be tidally locked, meaning the same side would always face it. This side would be incredibly hot, while the shadow side would be frozen which makes it hard for life to develop.
Another problem is that all the gravitational forces of the red dwarf could squeeze the planet and heat it up so much that it might lose all its water over time. These planets could end up like Venus, a hot burning hell.
On the other hand, their extremely long life span is a big plus. A red dwarf with just moderate levels of activity could be an amazing place for a planet that hosts life. Life on Earth has existed for about four 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. About 5% of the red dwarfs in the Milky Way may host habitable, roughly Earth-sized planets. There are an estimated 60 billion of these potentially habitable planets around red dwarfs, and that’s in the Milky Way alone, so red dwarfs might become really important for humanity’s 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 in the universe 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 its fuel completely. After its fuel is spent, it’s transformed into a white dwarf, an object about as small as Earth,packed very densely. Having no more source of energy, it will cool extremely slowly over trillions of years until it becomes its final form: a cold black dwarf.
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