Webb telescope provides the most detailed insight into the interior of a supernova yet

“Like a shiny, round ornament, ready to be hung in the perfect spot on the Christmas tree,” the remains of Cassiopeia A shine, NASA wrote on Tuesday.

The new image from the James Webb Telescope shows Cassiopeia A (also called Cas A) – one of the best-studied supernova remnants in our Milky Way.

When a massive star reaches the end of its life cycle, it collapses and explodes in a so-called supernova. Thanks to current technology – and the most powerful telescope ever launched into space – the remains of such a star explosion can also be observed here.

For example, in the constellation Cassiopeia, which is about 11,000 light-years away from Earth. A stellar explosion took place there around 1680. Cassiopeia A is now the name given to the expanding shell of material left behind by such an explosion – that is, the remnant.

Supernovas like the one that gave rise to Cas A are crucial to life as we know it: they spread elements like the calcium in our bones and the iron in our blood throughout the universe, creating new generations of stars and planets.

Cas A is the youngest known remnant of an exploding massive star in our Milky Way. It offers astronomers the opportunity to conduct so-called stellar forensics to better understand the death of a star.

“We’ve never looked at an exploded star like this before,” astronomer Dan Milisavljevic, assistant professor of physics and astronomy at Purdue University, said in a statement. “Supernovae are the main driving forces behind cosmological development.” Much depends on our understanding of supernovae, says the astronomer. “This is the best look we’ve ever had at a supernova in our Milky Way.”

In April, James Webb showed us a photo of Cas A. However, the photo that has now been published looks very different: both photos show certain features that are not visible in the other.

The difference between the images is due to the different wavelengths used: The most recent image was taken with a near-infrared camera (called NIRCam). This allowed the supernova remnant to be observed at different light wavelengths than those used in previous observations. However, the earlier image was taken with the mid-infrared camera (called MIRI) on the James Webb telescope.

The telescope observes the universe in wavelengths of infrared light that are invisible to the human eye. When the data is processed, the light captured by the telescope is converted into a color spectrum visible to humans.

The new NIRCam image shows orange and pink “flashes of color” within the inner shell of the supernova remnant. The colors resemble gaseous knots of elements emitted by the star. These include oxygen, argon, neon and sulfur.

“With the resolution of the NIRCam, we can now see how the dying star completely disintegrated during its explosion, leaving behind filaments that look like small pieces of glass,” says astronomer Milisavljevic.

What’s missing from the new image compared to the “old” image is something called the “Green Monster”: a circle of green light in the center of the remnant. The ‘Green Monster’ baffled astronomers after the image was published.

What stands out in the new image is a ‘spot’ nicknamed ‘Baby Cas A’, which can be seen at the bottom right. The spot resembles a smaller version of the supernova remnant and is located 170 light-years behind Cassiopeia A. But this time it’s no mystery, as CNN explains: it’s a so-called light echo, in which the light from the supernova interacts. dust from the galaxy interacted and caused it to warm up.

The whole thing is “breathtaking,” says Milisavljevic, who led a project team that contributed to the new image. “Some features have emerged that are completely new and will change our understanding of stellar life cycles.” (lacquer)