For the first time, the remains of an exploding star have been examined in detail.
Using a telescope attached to an observatory launched into space last year, astronomers mapped and measured polarized X-rays from the remnants of the dead supernova Cassiopeia A.
NASA and the Italian Space Agency have teamed up to develop the Imaging X-ray Polarization Probe (IXPE), which was launched into orbit last December.
It has three telescopes designed to measure scans of black holes, stars and other interstellar phenomena.
NASA said Cassiopeia A was chosen because it produced some of the fastest shock waves ever measured in the Milky Way when it collapsed.
The star has been previously studied using radio telescopes and NASA’s older Chandra X-ray Observatory, and the new composite image released by NASA was produced using data from these and IXPE.
Astronomers were surprised by IXPE’s findings, especially regarding the behavior of a star’s magnetic field.
What is a magnetic field?
For those of us at home, they put magnets on the fridge.
Fields push and pull moving charged particles, such as protons and electrons – in the case of exploding stars, these forces are much greater, and magnetic fields are able to lift these particles to almost the speed of light.
Cassiopeia A’s magnetic field is so strong that particles are trapped, forced to circle after its shock wave, and emit a strongly polarized light called “synchrotron radiation.”
What do we mean by polarized light?
Think of light as a wave that vibrates up and down at different angles.
When light is polarized, these waves vibrate at only one angle.
There’s another great example to help explain this: your sunglasses.
All forms of light can be polarized, and in the case of sunglasses, they help our eyes control the glare of sunlight.
With IXPE, its detectors can track incoming X-ray light, from where scientists can better understand what’s going on inside Cassiopeia A.
What did NASA scientists discover?
As far as astronomers go, it looks messy there.
Previous studies using radio telescopes have shown that almost the entire corpse of a star produces synchrotron radiation.
The scientists hypothesized that the X-ray polarization would result from a magnetic field perpendicular to those previously observed by radio telescopes.
But IXPE produced unexpected results, where the magnetic field in the X-rays instead aligned radially, sometimes very close to the shock wave, and polarized light much less than previously found.
NASA said it showed that the X-rays were taken in extremely turbulent regions of the stellar remnant, where a mix of magnetic fields pushes and pulls in all directions.
The dotted lines on this image reflect the different orientations of the magnetic field on the stellar remnant.Image: NASA
“These IXPE results were beyond our expectations, but as scientists, we like to be surprised,” said Dr. Jacco Vink, a researcher at the University of Amsterdam and lead author of the paper describing the IXPE findings.
“The fact that a smaller proportion of X-ray light is polarized is a very interesting and previously undiscovered property of Cas A.”
Co-author Dr Riccardo Ferrazzoli said the star’s remains have proven to be an “astrophysical laboratory” for astronomers to test new equipment and techniques.
“We’ve only just begun this detective story, but so far, the IXPE data has given us new clues to follow,” he added.
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