What is Cassiopeia A, popularly known as the Green Monster of Space?

NASA's James Webb Space Telescope has spied on the glowing gas and dust of the never-before-seen 'Cassiopeia A' also popularly known as the Green Monster of Space by scientists. James Webb Space Telescope captured the colourful details closely on the most well-observed remnants of an exploded star. The supernova Cassiopeia A is approximately 340 years old from Earth’s perspective. It is formed from a dramatic explosion of a star and the remnants that are left behind during this stellar galactic event.

James Webb shot a new mid-infrared image showing the supernova remnant Cassiopeia A (Cas A), which was created by a stellar explosion that caused glowing gas and dust. Its light reached Earth for the first time 340 years ago. Cassiopeia A is the youngest known supernova remnant in the galaxy, and it is one of the most researched and observed celestial objects that is seen from ground and space-based telescopes.

Credit: NASA

Stellar autopsy 1,000 light-years away

Located 11,000 light-years away in the Cassiopeia constellation, the remnants of the Cassiopeia A stretch for approximately 10 light-years. Insights from Cas A will help scientists study how stellar explosions occur in space. “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,” Danny Milisavljevic of Purdue University in West Lafayette, Indiana, principal investigator of the Webb program that captured these observations was quoted as saying in the NASA release. 

“Compared to previous infrared images, we see incredible detail that we haven't been able to access before,” Tea Temim of Princeton University in Princeton, New Jersey, a co-investigator on the program said in a NASA statement.

Webb telescope and its instruments were turned in the direction of Cas A as the astronomers wanted to look at the observatory’s infrared capabilities. Infrared light is invisible to the human eye, and Webb can capture galactic entities not easily visible in the universe outside. Cassiopeia A, according to NASA is a prototypical supernova that was also observed at NASA’s Chandra X-ray Observatory. The multi-wavelength observations can be combined to provide scientists with a more comprehensive understanding of the remnant, the space agency said.  Among the science questions that Cas A may help answer NASA is: Where does cosmic dust come from? Young galaxies in the early universe as per the previous observations were found suffused with massive quantities of dust. And it has been difficult to explain the origins of this dust without invoking supernovae, which spew large quantities of heavy elements across space.