Skip to main content

Gas at 20 million degrees glows brightly in this colorful supernova remnant

This X-ray and optical image of Cassiopeia A (Cas A) combines images captured by the Chandra X-ray Observatory and the Hubble Space Telescope X-ray: NASA/CXC/SAO; Optical:NASA/STScI

NASA’s Chandra X-ray Observatory has returned to the first target it imaged 20 years ago to collect an updated image. This glowing cloud is the remnant of a supernova which is believed to have exploded in the year 1680. When the Cassiopeia A star reached the end of its life and ran out of fuel, it collapsed to a dense core before exploding in an enormous outpouring of energy. This explosion generated shock waves that illuminated the stellar debris around it, making it glow particularly in the X-ray spectrum.

The X-ray spectrum is the wavelength that Chandra observes, and so Cassiopeia A glows brightly and colorfully in Chandra images. In the image above, the colorful cloud is an X-ray image, which has Hubble’s visible-light image of yellow stars imposed on top of it.

A Tour of the Latest Look at "First Light" from Chandra

Cassiopeia A is somewhat famous for being the “first light” image of Chandra — that is, the first target chosen for the inauguration of the then-new telescope in 1999. Below, you can see that 20-year-old image and get an idea of how both the remnant and our ability to image it have developed over time.

Chandra’s first light image of Cassiopeia A, taken in 1999. NASA/CXC/SAO

We’ve also learned a lot about Cassiopeia A in the last 20 years. We now know, for example, that the gas in the outer shell of the remnant is incredibly hot, at 20 million degrees Fahrenheit, with filaments of cooler gas at 20,000 degrees Fahrenheit running through it. We also know that the blue edges of the remnant are expanding outward as a blast wave traveling at 11 million miles per hour, composed of shock waves which NASA describes as “similar to the sonic booms generated by a supersonic aircraft.” The particles in this area of shock waves are accelerated to tremendous energies, reaching twice as much energy as particles do in the Large Hadron Collider.

Recommended Videos

Previous work from Chandra has also revealed information about the composition of Cassiopeia A. We know it is composed of silicon (which appears red in the top image), sulfur (in yellow), calcium (in green), and iron (in purple). These elements produce different X-rays, which is how Chandra is able to differentiate them and show their distribution in the remnant in gorgeous color.

Georgina Torbet
Georgina has been the space writer at Digital Trends space writer for six years, covering human space exploration, planetary…
Hyundai Ioniq 5 sets world record for greatest altitude change
hyundai ioniq 5 world record altitude change mk02 detail kv

When the Guinness World Records (GWR) book was launched in 1955, the idea was to compile facts and figures that could finally settle often endless arguments in the U.K.’s many pubs.

It quickly evolved into a yearly compilation of world records, big and small, including last year's largest grilled cheese sandwich in the world.

Read more
Global EV sales expected to rise 30% in 2025, S&P Global says
ev sales up 30 percent 2025 byd sealion 7 1stbanner l

While trade wars, tariffs, and wavering subsidies are very much in the cards for the auto industry in 2025, global sales of electric vehicles (EVs) are still expected to rise substantially next year, according to S&P Global Mobility.

"2025 is shaping up to be ultra-challenging for the auto industry, as key regional demand factors limit demand potential and the new U.S. administration adds fresh uncertainty from day one," says Colin Couchman, executive director of global light vehicle forecasting for S&P Global Mobility.

Read more
Faraday Future could unveil lowest-priced EV yet at CES 2025
Faraday Future FF 91

Given existing tariffs and what’s in store from the Trump administration, you’d be forgiven for thinking the global race toward lower electric vehicle (EV) prices will not reach U.S. shores in 2025.

After all, Chinese manufacturers, who sell the least expensive EVs globally, have shelved plans to enter the U.S. market after 100% tariffs were imposed on China-made EVs in September.

Read more