Historic! NASA’s IXPE captures image of Crab Nebula, the ‘mysterious supernova remnant’

Over the weekend, the United States space agency, National Aeronautics and Space Administration (NASA) released an image of the Crab Nebula which it said was one of the well-known as well as mysterious astronomical objects in our night sky.

The bright cosmic object is 6,500 light-years away, in the Taurus constellation, the image of which was captured by using NASA’s Imaging X-ray Polarimetry Explorer (IXPE), which launched on December 9, 2021.

What makes this image historic?

There is a long history behind the recently released image as the sensors which had been directed at the Crab Nebula were first launched in a sounding rocket back in 1971. However, scientists back then would first receive scientific data on a strip chart recorder, a device that printed signals on paper. For this project, astronomer Martin Weisskopf and his colleagues began their analysis on launch day by measuring the distance between signals using a ruler and pencil.   

It was not until a few decades later that the astronomer proposed developing a satellite with “powerful instruments” which would help them gather more detailed measurements of the Crab Nebula and other mysterious cosmic objects. This led to the creation of IXPE and now over five decades later scientists have a nuanced map of the Crab Nebula’s magnetic field. 

“What makes science so beautiful and exciting is that for those few moments, you’re seeing something that no one has ever seen before,” said Weisskopf, in a statement, who is now an emeritus astronomer at NASA. The Crab Nebula is also the result of a supernova documented in the year 1054, said the space agency. 

The explosion left behind a dense object called the Crab Pulsar, about the diameter of the length of Manhattan with the mass of about two Suns. “The chaotic mess of gases, shock waves, magnetic fields and high-energy light and particles coming from the rotating pulsar is collectively called a ‘pulsar wind nebula,’” NASA explained. 

However, the extreme conditions which resulted in this “bizarre environment” have not been thoroughly understood. Even after so many years, “every recent large telescope has pointed to the Crab Nebula to better understand this mysterious supernova remnant,” said NASA, in a statement.

“The Crab is one of the most-studied high-energy astrophysical objects in the sky. So it is extremely exciting that we could learn something new about this system by looking through IXPE’s ‘polarized lenses,’” said Michela Negro, a research scientist at NASA and co-author of the study.

What did the scientists find?

While the image of the nebula is a sight to behold it was actually the Crab Nebula’s magnetic field that the scientists wanted to understand more about. According to NASA, the map has revealed “more of its inner workings than ever before.” 

The researchers observed that the magnetic field of the Crab Nebula resembles that of the Vela Pulsar Wind Nebula, which is also doughnut-shaped, however, they were surprised by how parts of the magnetic field turbulence “more patchy and asymmetrical than expected.” 

It was the previously mentioned “bizarre environment” that Weisskopf and colleagues were hoping to understand by measuring the polarisation of X-rays from the Crab Nebula. This is because the polarisation of X-ray gives scientists clues to the direction where the magnetic field points in different parts of a cosmic object, as well as how well-ordered the magnetic field is.  

“The magnetic field’s geometry and turbulence determines how particles get catapulted toward the speed of light,” said NASA. Scientists found that the areas of polarisation in the outer regions of the nebula are light-years away from the pulsar, where polarisation is lower. 

This has enabled them not only to investigate the X-rays from the Crab Nebula but also those coming from the pulsar itself. “The findings suggest that those X-rays originate in the outer magnetic field region, called the ‘wind’ region, although exactly where and how is still unknown,” said NASA.