No one saw this star explode in the 17th century, but luckily we have James Webb

No one saw this star explode in the 17th century, but luckily we have James Webb

In the 17th century, a star exploded in the constellation Cassiopeia. This star was at least eight times more massive than our Sun. Now – 340 years later – the James Webb Telescope is imaging this brightest radio source in the sky.

In a few hundred years the rest has grown exponentially. Cassiopeia A is now about ten light-years in diameter. In the center of the nebula is a compact object. This could be a black hole or a neutron star. Fun Fact: Cassiopeia A was only discovered in 1947. The light from the explosion reached our solar system in 1667, but no one on Earth seems to have noticed this stellar explosion.

The supernova remnant appears colored in the latest web image. However, these are not colors that we can see with the human eye. The space telescope has cameras on board that capture infrared light. The human eye can only see infrared light under certain conditions. So the researchers translated infrared light into visible light.

The orange and red regions show cosmic battlefields: here material from the exploding star collides with surrounding gas and dust. This causes the fabric to heat up. In the center of the remains we see pink gas masses. This is a glowing material from a star, consisting mainly of heavier elements such as oxygen, argon, and neon. This part of the nebula is also visible in visible light. Place the Hubble image next to it and you’ll see that the pink gas is all that’s left.

The James Webb image shows more detail than the Hubble image because James Webb captures infrared light and has a much larger mirror.

Where does cosmic dust come from?
Astronomers hope Cassiopeia A will answer an important question: Where does all the cosmic dust come from? The first galaxies in the young universe already contain countless dust particles. It seems plausible that exploding stars jumped (and still spew) these dust particles into space, but the amounts are so large that scientists have found no explanation after observing so many supernovae. Who knows, Cassiopeia A might shed more light on this mystery. By the way, did you know that tons of cosmic dust particles fall to the Earth’s surface every day? The Earth does not gain weight because of this: our planet also loses many gases such as hydrogen and helium every day.

One thing is certain: without supernovae like Cassiopeia A, life as we know it could not have arisen. Supernovae produce heavy elements such as calcium and iron, from which new stars and planets are born. The calcium in your bones or the iron in your blood also originated in this way. Fascinating!

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