Astronomy & Space

A new Webb telescope picture exposes star structure mysteries and the building elements of life.

Humans can and do look up at the stars. It’s almost divine to be able to see them in three dimensions.

A new, in-depth image of Cassiopeia A (Cas A), a stellar remnant—the clouds of gas, dust, and other materials left behind when a star dies—that was captured by the James Webb Space Telescope has given earthbound scientists a glimpse into the divine. A year-one research team on the JWST looking at Cas A is led by Danny Milisavljevic, assistant professor of physics and astronomy in the College of Science at Purdue University. Danny studies supernova remnants.

I have devoted the last 17 years to researching stars and their titanic explosions. I’ve used numerous telescopes, both on the ground and in space, to study the electromagnetic spectrum, from gamma rays to radio wavelengths, Milisavljevic said. The information that Webb provided, however, still caught me off guard. By their excellence and beauty, I am in awe.”.

“I’ve spent the last 17 years researching stars and their titanic explosions.” I’ve employed hundreds of ground- and space-based telescopes to cover the electromagnetic spectrum from gamma rays to radio frequencies.”

Danny Milisavljevic, assistant professor of physics and astronomy in Purdue University’s College of Science.

Cassiopeia A presents an exceptional opportunity to learn more about how such supernovae happen because it is the youngest known remnant from an exploding, massive star in our galaxy. It took 340 years for the light from its explosion to reach Earth.

According to Milisavljevic, “Cas A represents our best opportunity to look at the debris field of an exploded star and conduct a sort of stellar autopsy to understand what kind of star was there initially and how that star exploded.”

Life depends on supernovae like the one that created Cas A. Every element in our bodies, from the calcium in our bones to the iron in our blood, is produced by stars and subsequent supernovae, which spread these elements throughout interstellar space and seed new generations of stars and planets.

“We are reading our own origin story by comprehending how stars explode,” Milisavljevic claimed.

looking through fresh eyes.
The remnant is in the area of the sky thought to belong to the constellation Cassiopeia, located about 11,000 light-years away. Cas A, a grouping of five bright stars in the shape of a “W,” is hidden from Earth’s perspective and only visible through telescopes. It is located in the area that appears to be off to the right of the W’s final stroke.

Cas A has been the subject of extensive scientific research. Similar to how infrared cameras provide humans with different information than cameras that only see in the visible light spectrum, examining the structure using different wavelengths offers astronomers new insights into star anatomy.

Incredibly fine detail can be seen in the newly acquired image from the JWST’s golden honeycomb of 18 mirrors. It converts mid-infrared light into visible light, enabling researchers to study structures and small details. Where the star’s material is colliding with the surrounding gas and dust, it is represented by large curtains of material that are shaded red and orange. Bursts of pink indicate the locations of the star’s composite elements, such as oxygen, argon, and neon, among those rosy swaths.

The large green loop on the right side of the image is one of the image’s most perplexing features for the researchers.

In honor of Boston’s Fenway Park, Milisavljevic said, “We’ve given it the nickname the Green Monster. You can see that it is spotted with what appear to be small bubbles if you pay close attention. The shape and complexity are unexpected and difficult to comprehend.”.

Astronomers can see the structure’s intricate details more clearly with higher resolution images taken at more wavelengths, especially the infrared. The more information scientists have, the more they can infer and analyze, similar to using binoculars to help distinguish between the colors and patterns on a bird’s wing.

Tea Temim, a program co-investigator from Princeton University, said, “Compared to previous infrared images, we see incredible detail that we haven’t been able to access before.”

Ashes to ashes
Contrary to expectations, some of the most fascinating objects in the image might appear to be the most commonplace: dust. While the substance irritates housekeepers, astronomers find it fascinating.

Even the youngest galaxies in the early universe are engulfed in enormous amounts of dust. It is challenging to account for the origins of this dust without mentioning supernovae, which eject massive amounts of heavy elements, the constituents of dust, into space.

It is unclear how much dust makes it to interstellar space because supernovae can also destroy it. Astronomers hope to learn more about Cas A’s dust content by observing it with JWST. This knowledge can help us better understand how planets and humans are formed.

In Cas A, Temim explained, “We can spatially resolve regions with different gas compositions and look at what types of dust were formed in those regions.”.

We are made of “star stuff,” as Carl Sagan famously reassured humanity. The observations made by JWST and the Milisavljevic team assist scientists in understanding that process.

Milisavljevic remarked that Webb’s accomplishment was remarkable. “I consider myself fortunate to be one of the pioneering researchers who tested its unparalleled capacity to delve into the cosmos. I’ll be attempting to comprehend what’s in this data set for the remainder of my professional life.”.

Provided by Purdue University 

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