NASA's James Webb Space Telescope (JWST) captured new images revealing intricate patterns in the interstellar medium, illuminated by the light echo of the supernova Cassiopeia A. The observations provided astronomers with a rare glimpse into the complex structures of gas and dust in space, offering insights into the aftermath of stellar explosions and the formation of new stars.
The JWST's recent imaging of Cassiopeia A unveiled the effects of the centuries-old supernova, capturing the infrared glow of gas and dust heated by the shock wave from the explosion. Universe Today explains that the shock wave heated nearby clouds of gas and dust, causing them to glow in the infrared range, which was detected by the JWST.
"The emerging layers are just like the rings of an onion," said Dr. Jacob Jencson, a member of the research team, according to Discover Magazine. "We were pretty shocked to see this level of detail."
The images from the JWST revealed intricate, never-before-seen patterns in the interstellar medium, including dense regions that resemble knots and whorls found in wood grain, likely sculpted by magnetic fields. Both sheet-like features and dense knots in the interstellar medium are thought to be related to interstellar magnetic fields.
"We think every dense, dusty region that we see, and most of the ones we don't see, look like this on the inside. We just have never been able to look inside them before," said Josh Peek of the Space Telescope Science Institute, according to Fox News.
The observations from the JWST allowed astronomers to map the three-dimensional structure of the interstellar medium for the first time. This ability opens up opportunities to study the true 3D structure of the dust and gas that fill interstellar space.
The images also revealed tightly packed sheets of interstellar material with structures on "remarkably small scales," about 400 astronomical units or less than one-hundredth of a light year. These filaments exhibit structures on scales previously unobserved in the interstellar medium.
The findings were presented at the 245th meeting of the American Astronomical Society in National Harbor, Maryland.
A light echo is created when a star explodes or erupts, flashing light into surrounding clumps of dust and causing them to shine in an ever-expanding pattern. Discover Magazine explains that the JWST witnessed the reflection of this light pulse as it bounced off the surrounding gas and dust while traveling through the interstellar medium.
The configuration of the structures within the interstellar medium could be influenced by magnetic fields. Both the sheet-like features and dense knots are thought to be related to these fields. These magnetic fields may play a role in how gas sheds magnetic support, which is essential for allowing gas to collapse and form stars.
The JWST images also show dense, tightly wound regions that resemble knots in wood grain, referred to as magnetic islands. Space.com notes that these regions may represent magnetic islands embedded within the more streamlined magnetic fields that permeate the interstellar medium.
Researchers plan to observe multiple light echoes a few weeks or months apart to study how they evolve as they pass through the interstellar medium. This ongoing observation will help scientists track the thermal light echo's development using the telescope's Mid-Infrared Instrument (MIRI).
"We can observe the same patch of dust before, during, and after it's illuminated by the echo and try to look for any changes in the compositions or states of the molecules, including whether some molecules or even the smallest dust grains are destroyed," said Jencson, as reported by Discover Magazine.
Interstellar space is filled with gas and dust clouds, often invisible unless illuminated, consisting of leftover ingredients from galaxy formation, star debris, and the building blocks for future stars and planets. Mashable explains that the JWST excels at observing and detailing the infrared range, allowing it to penetrate dust and gas that obscure distant light sources.
The JWST's ability to reveal the fine-grained structure of the interstellar medium for the first time will help astronomers build a 3D map of its structures, providing important clues about its true nature.
"This is going to completely change the way we think about the foundations of the cold interstellar medium," said Josh Peek, according to Space.com.
This article was written in collaboration with generative AI company Alchemiq