About 340 years ago, long before the United States was a country, light that had traveled through space and time from a huge exploding star finally reached Earth.
Cassiopeia A, the wispy kaleidoscope of colors swirling in this image, is the youngest-known supernova remnant in the Milky Way. That makes it a profoundly unique cosmic object for astronomers to study, perhaps shedding light on how such cataclysmic star deaths occur.
“Cas A represents our best opportunity to look at the debris field of an exploded star and run a kind of stellar autopsy to understand what type of star was there beforehand and how that star exploded,” said Danny Milisavljevic of Purdue University in Indiana, in a statement.
Milisavljevic and other scientists recently captured new observations of Cassiopeia A, called “Cas A” for short, with the James Webb Space Telescope, the preeminent infrared observatory in orbit, run by NASA and the European and Canadian space agencies. Some astronomers have gone so far as to call it the best Webb image yet, revealing much more detail than ever before.
Spectacular Webb telescope image shows a stellar death like never before
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Because infrared light is invisible to human eyes, researchers have translated the data into visible-light wavelengths, sort of like playing the same tune but in a lower octave. The new image could be thought of as the gas and dust that rise from the ashes of stellar death.
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The Cas A remnant spans about 10 light-years and is located 11,000 light-years away in the constellation Cassiopeia. In the new photo, it’s revealed as a bubble with curtains of fiery red and orange material, caused by warm dust. Within it is a ring of hot pink threads and knots, material from the dead star. It’s shining because of a mix of heavy elements, such as oxygen, argon, and neon, scientists say.
“a kind of stellar autopsy … ”
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The research team nicknamed the green loop, found a little right of the center, “the Green Monster” in honor of the Red Sox’s Fenway Park in Boston. It’s dotted with more tiny, intriguing bubbles that they don’t fully understand. Scientists are still trying to tease out all the emission sources.
Supernovas like Cas A are element factories, astrophysicists say: They make carbon, for instance, the same chemical on which humans and much of life on Earth are based. They spread metals like calcium found in bones and iron in blood across interstellar space. This dispersal seeds new generations of stars and planets.
“By understanding the process of exploding stars, we’re reading our own origin story,” Milisavljevic said. “I’m going to spend the rest of my career trying to understand what’s in this data set.”
