SPACE — The sun will one day become a red giant star. What is a red giant?
Red giants are stars that are going through their death stages. A dying star slowly swells to many times its original size.
Reporting from EarthSky, when a star becomes a red giant, it may remain in that state for up to a billion years. Then the star will slowly contract and cool until it becomes a white dwarf.
The opposite of red giants, white dwarfs are extremely dense stars the size of Earth that emit a fraction of their original energy. Eventually, after billions of years, these stars will become very cold and emit no energy.
This star will then end its life as a so-called black dwarf. A black dwarf is a tiny piece of ash that burns out and is barely visible.
To become a red giant, a given star must have a mass between half that of our sun and eight times that of our sun. Astronomers call these stars low and medium mass stars.
How long do red giants last?
According to theory, a star will be in the red giant phase for about a billion years. What happens next will depend on the mass of the star.
High mass stars will explode as supernovae. Low to medium mass stars like our Sun will slowly shrink and cool to become white dwarf stars.
If you look at the sky, there are several red giants with the naked eye. Aldebaran is one example.
Keep in mind, however, that two other famous red beasts, Antares and perhaps the most famous. Apart from that there is the star Betelgeuse, which is a red supergiant.
Red supergiants are the final stages of much larger stars. This star will explode in a supernova before becoming a neutron star or even a black hole (depending on its mass).
Betelgeuse famously made headlines a few years ago when it suddenly started dimming, for several months in 2019. Its brightness dropped by more than 60 percent, meaning the night sky felt dimmer.
What about the sun?
According to the theory, over the next few hundred million years, the sun’s brightness will slowly increase and begin to emit more energy across the electromagnetic spectrum. At that time the sun was entering its subgiant phase.
In about a billion years, increasing radiation from the sun will sterilize Earth and wipe out all life.
2023-11-11 09:28:00
#Scientists #sun #red #giant
