Explained | Will Betelgeuse, the red giant star, blow up in your lifetime?

Source: The post is based on the article “Explained | Will Betelgeuse, the red giant star, blow up in your lifetime?” published in The Hindu on 22ndJune 2023

What is the News?

Researchers from Japan and Switzerland have recently reported that Betelgeuse is in its late carbon-burning stage.

In massive stars like Betelgeuse, the carbon-burning stage lasts only up to a few hundred years, after which the star ‘dies’ and collapses into a supernova within a few months.

What is Betelgeuse?

Betelgeuse is a red supergiant star with a distinctive orange-red hue. Stars in this class are nearing the end of their lives. It is easily spotted in the constellation Orion

Note: A red giant forms after a star has run out of hydrogen fuel for nuclear fusion and has begun the process of dying

In Indian astronomy, Betelgeuse is called ‘Thiruvathirai’ or ‘Ardra’.

Betelgeuse is about 640 light-years away. This means that it takes the light from this star 641 years to reach Earth.

Betelgeuse is particularly easy to spot because of its brightness. It is often the tenth-brightest star in the sky. (It can be much brighter or much dimmer at times). Betelgeuse is about 7,500 to 14,000 times brighter than the Sun.

How have astronomers found that Betelgeuse is in its late carbon stage?

Astronomers have suggested the stage of the red giant star Betelgeuse by studying its pulsations. 

Betelgeuse undergoes periodic expansion and contraction (similar to a boiling pot releasing steam), causing variations in its brightness. By analyzing these pulsations, researchers can infer the star’s current state.

Life Cycle of Betelgeuse

Massive stars like Betelgeuse run out of hydrogen fuel in only a few crore years, when they switch to using helium to make carbon.

The energy released in the fusion of helium is less than that of hydrogen, so the star burns more helium to stay stable and not collapse. The helium runs out in about ten lakh years.

At this time, red giants like Betelgeuse burn carbon, then silicon, and briskly consume one by one the elements of the periodic table, until finally their core brims with iron– whose fusion requires more energy than it releases – and some cobalt and nickel.

Once the core is rich in iron, the temperature and pressure within the star drop. With nothing to stop it, gravity compresses the core and turns it into a neutron star or a black hole.