Not since 1604 have human eyes witnessed a supernova directly.
However, two Milky Way supernovae occurred subsequently.
Cassiopeia A was a core-collapse supernova in the galactic plane, occurring between 1667-1680.
G1.9+0.3, near the galactic center, occurred around 1868.
Discovered only in 1947, Cassiopeia A is the brightest radio source beyond our Solar System.
In visible light, there’s very little to see: like a fast-fading firework.
In X-ray light, its heated gases shine brilliantly.
Infrared views, however, are most revealing, showcasing various elements and turbulent knots.
At long last, JWST’s views, with both NIRCam and MIRI, are now public.
At just ~350 years old, the remnant is already 10 light-years across.
The “shell” of ejecta expands at 1.5% the speed of light, with jets reaching nearly ~5% of lightspeed.
Internally, “bubbles” appear, providing evidence for the underlying shape of the gas distribution.
Incredibly bright, near-infrared regions highlight dense filaments of heated material.
Layers of the exploded star currently collide with the surrounding circumstellar matter.
The explosion’s ejecta reveals numerous elements: oxygen, neon, argon, calcium, and phosphorus among them.
The mid-infrared “wisps” provide clues for how collapsing stars expel material.
With so little hydrogen present, it shows how varied supernovae can be.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.