Credit: X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI; IR: NASA/ESA/CSA/STScI/Milisavljevic et al., NASA/JPL/CalTech; Image Processing: NASA/CXC/SAO/J. Schmidt and K. Arcand
Studying a Dying Star from the Outside In
Chemical elements heavier than helium are mainly produced in the cores of massive stars. These elements are distributed to the Galaxy when these stars explode as supernovae. Supernova explosions produce huge clouds of enriched hot gas which distributes newly-formed chemical elements from the stellar interior into a volume of space of a few thousand cubic light-years. X-ray observatories are key instruments used to study young supernova remnants, since the powerful explosion produces gas that is extremely hot (millions of degrees). The Chandra X-ray telescope has given us an incredibly detailed view of how the hot enriched gas is spread into space in a supernova remnant called Cassiopeia A (Cas A for short), the (approximately) 340 year-old remnant produced by the explosion of a massive star. Now, a new study of Cas A by the Resolve high resolution spectrometer on XRISM (the X-ray Imaging and Spectroscopy Mission), a JAXA/NASA/ESA X-ray space observatory has clearly detected X-rays emitted from the chemical elements chlorine and potassium for the first time. These two elements are critical for life to exist but not very abundant in the Universe, so the Resolve data are important for understanding how stars create and distribute such complex elements into the cosmos. The Resolve spectra showed that the relative abundance of these elements in some regions of Cas A was higher than expected based on current theory. The image above shows a deep, high-resolution X-ray image of Cas A from the Chandra X-ray Observatory, combined with optical and infrared images. The grid superimposed on the image shows the XRISM Resolve field of view for two separate observations, one of the northwestern part of the remnant and one to the southeast. The green squares show regions where the Resolve spectra showed enhanced potassium, while the yellow squares in the west showed weaker evidence for potassium. This spatial difference may suggest a non-uniform distribution of potassium inside the star just before it exploded.
Published: December 8, 2025
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Page Author: Dr. Michael F. Corcoran
Last modified Monday, 15-Dec-2025 12:47:00 EST