Remains of a star that exploded 36 years ago have captured the attention of the James Webb Space Telescope and its NIRCam. Telescope has immortalized the expanding stellar debris, revealing new details about the supernova remnant 1987A. Located approximately 168,000 light-years from Earth in the Large Magellanic Cloud, it represents the demise of a blue supergiant star called Sanduleak-69 202.
Before it exploded, that star was thought to have a mass about 20 times that of the Sun. 1987A is so bright that it’s visible to the naked eye in the southern hemisphere. Astronomers have always tracked the traces of its expanding debris.
Study of 1987A
With the James Webb, the remnants of supernova 1987A have been captured with unprecedented detail. And thanks to these images, a study (ref.) conducted by Mikako Matsuura of Cardiff University has emerged. The project used the James Webb to measure the shockwave of the expanding supernova. When massive stars, like blue supergiants, approach the end of their lives, they become unstable and begin to eject large amounts of matter.
Hubble Space Telescope previously observed the expanding shockwave of Supernova 1987A. It was calculated to initially travel at about 7,000 kilometers per second, colliding with a ring of circumstellar debris ejected by the star. When the shockwave collided with this ring, it slowed down to a speed of about 2,300 kilometers per second.
Clumps within this ring gradually lit up. Two other rings, seemingly in a different plane from the main one, are more mysterious. Astronomers have hypothesized that these rings may be located where the star’s stellar wind interacts with previously expelled material from the star.
Neutron Star Hypothesis
Alternatively, they could be illuminated by jets from an invisible neutron star. According to experts, it formed alongside the supernova explosion. James Webb has revealed new details about Supernova 1987A. Shockwave has expanded beyond the main ring and has reaccelerated to about 3,600 kilometers per second. This has produced new hotspots that could, over time, become as bright as those previously identified.
Additionally, there is also a more diffuse emission in the form of a glow. The supernova shockwave likely excites the gas around the explosion site. But there’s more to it, james Webb has spotted two arcs or crescents within the main ring. These features, the team suggests, could represent the outer layers of gas ejected by the supernova.
James Webb will continue to monitor the evolving supernova remnant as well as search for the neutron star at the center of the explosion, which has not been seen so far. However, there are indirect pieces of evidence for the neutron star in the form of X-ray emissions detected by NASA‘s Chandra and NuSTAR X-ray observatories. Observations from the Atacama Large Millimeter/submillimeter Array (ALMA) also indicate that the neutron star may be hidden in one of the dust clumps at the heart of the remnants.