This new NASA/ESA/CSA James Webb Space Telescope Picture of the Month features a cosmic creepy-crawly called NGC 6537 – the Red Spider Nebula. Using its Near-InfraRed Camera (NIRCam), Webb has revealed never-before-seen details in this picturesque planetary nebula with a rich backdrop of thousands of stars.
Planetary nebulae like the Red Spider Nebula form when ordinary stars like the Sun reach the end of their lives. After ballooning into cool red giants, these stars shed their outer layers and cast them into space, exposing their white-hot cores. Ultraviolet light from the central star ionises the cast-off material, causing it to glow. The planetary nebula phase of a star’s life is as fleeting as it is beautiful, lasting only a few tens of thousands of years.
The central star of the Red Spider Nebula is visible in this image, glowing just brighter than the webs of dusty gas that surround it. The surprising nature of the nebula’s tremendously hot and luminous central star has been revealed by Webb’s NIRCam. In optical-wavelength images, such as from the NASA/ESA Hubble Space Telescope, the star appears faint and blue. But in the NIRCam images, it shows up as red: thanks to its sensitive near-infrared capabilities, Webb has revealed a shroud of hot dust surrounding the central star. This hot dust likely orbits the central star, in a disc structure.
Though only a single star is visible in the Red Spider’s heart, a hidden companion star may lurk there as well. A stellar companion could explain the nebula’s shape, including its characteristic narrow waist and wide outflows. This hourglass shape is seen in other planetary nebulae such as the Butterfly Nebula, which Webb also recently observed.
Webb’s new view of the Red Spider Nebula reveals for the first time the full extent of the nebula’s outstretched lobes, which form the ‘legs’ of the spider. These lobes, shown in blue, are traced by light emitted from H2 molecules, which contain two hydrogen atoms bonded together. Stretching over the entirety of NIRCam’s field of view, these lobes are shown to be closed, bubble-like structures that each extend about three light-years. Outflowing gas from the centre of the nebula has inflated these massive bubbles over thousands of years.
Gas is also actively jetting out from the nebula’s centre, as these new Webb observations show. An elongated purple ‘S’ shape centred on the heart of the nebula follows the light from ionised iron atoms. This feature marks where a fast-moving jet has emerged from near the nebula’s central star and collided with material that was previously cast away by the star, sculpting the rippling structure of the nebula seen today.
The observations used to create this image come from Webb GO programme #4571 (PI: J. Kastner), which aims to understand how bipolar planetary nebulae like the Red Spider Nebula are shaped by the outflows and jets that emerge from the stars at their cores.
[Image Description: A large planetary nebula. The nebula’s central star is hidden by a blotchy pinkish cloud of dust. A strong red light radiates from this area, illuminating the nearby dust. Two large loops extend diagonally away from the centre, formed of thin ridges of molecular gas, here coloured blue. They stretch out to the corners of the view. A huge number of bright, whitish stars cover the background, also easily visible through the thin dust layers.]