The Crab Reveals Its Secrets To JWST

The Crab Nebula – otherwise known as the first object on Charles Messier’s list of non-cometary objects or M1 for short – has never really failed to visually underwhelm me! I have spent countless hours hunting down this example of a supernova remnant and found myself wondering why I have bothered. Yet here I am, after decades of looking at it, and I still find it one of the most intriguing objects in the sky.

Never has this interest been piqued more than right now after another mirror-smashing beauty of an image from the James Webb Space Telescope, and it’s already found its way to my mobile phone wallpaper!

The NASA/ESA/CSA James Webb telescope was launched back in December 2021, and from its position 1.5 million km away, it orbits the Sun, giving us a brand new window out into the Universe. Using its Near-Infrared Camera (NIRCAM) and the Mid-Infrared Instrument (MIRI) JWST has been exploring the Crab Nebula, the remains of a star whose explosion was recorded back in 1054. The object, which is 6,500 light years away, can be seen in small amateur telescopes and is without doubt one of the most studied supernova remnants of all. 

Despite being the target of many, many observations, there are still plenty of unanswered questions about the nature of the star that exploded, the mechanics of the explosion itself, and the composition of the ejecta.  Using JWSTs infrared capabilities, the image of the Crab reveals red/orange filaments of dust around the central region. The filaments weave an intricate pattern over the whole nebula, but it’s the core that has received more attention. 

Compare and contrast the Hubble version on the left with the new, Webb version on the right. Credit: NASA, ESA, CSA, STScI, T. Temim (Princeton University)

It has been known that there is a pulsar at the core of the nebula, and it’s this pulsar that is the true remains of the progenitor star.  When it went ‘supernova,’ the core collapsed to form the ultra-dense rotating object that, if you happen to be in the right place in space (hey, that rhymes), then you will see a pulse of radiation as it rotates. The infrared images from JWST reveal synchrotron emissions, which are a direct result of the rapidly rotating pulsar.  As the pulsar rotates, the magnetic field accelerates particles in the nebula to astonishingly high speeds such that they emit synchrotron radiation. As a fabulously lucky quirk of nature, the radiation is particularly obvious in infrared, making it ideal for JWST. 

Not only has JWST detected synchrotron radiation, but it has also mapped out locations of dust particles and even… locations where dust particles are forming. It’s fabulous to think that an object that was discovered almost a thousand years ago is still surprising us. That’s one of the things I love about astronomy: you think you have seen it all, but there is always more to learn.  Over the coming years, teams of astronomers using both HST and JWST will continue to probe the depths of the Crab Nebula, and maybe one day, all of its secrets will finally be revealed. 

Source: ESA JWST News Release