Astronomers from Welsh university help reveal striking new nebula image

Astronomers from a Welsh university have helped reveal never-before-seen details of the Red Spider Nebula, captured in a new image from the James Webb Space Telescope

The image, selected as JWST’s Picture of the Month, was captured using the telescope’s Near-InfraRed Camera (NIRCam), and shows the cosmic creepy-crawly against a backdrop of thousands of stars.

The observations used to create the image come from a joint programme, which aims to understand how bipolar planetary nebulae like the Red Spider Nebula, NGC 6537, are shaped by the outflows and jets that emerge from the stars at their cores.

Dr Mikako Matsuura, a co-investigator on the programme based at Cardiff University’s School of Physics and Astronomy, said: “Out in the vast darkness of the Universe, there are many eerie and ghostly nebulae.

“One of the most haunting is the Pillars of Creation, towering columns of gas and dust within the Eagle Nebula, captured by JWST in a breath-taking image in 2022.

“Among the many so-called ‘spider nebulae’, one stands out for its chilling resemblance to a cosmic creature: the Red Spider Nebula, whose twisted filaments stretch like the legs of a celestial arachnid.”

Picturesque planetary nebula like NGC 6537 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 extremely hot cores. Ultraviolet light from the central star ionises the cast-off material, causing it to glow.

The NIRCam’s sensitive near-infrared capabilities reveal a shroud of hot dust, which likely orbits the central star in a disc structure, according to the team of researchers led by Professor Joel H. Kastner of the Rochester Institute of Technology.

Though only a single star is visible in the Red Spider’s heart, the researchers believe a hidden companion star may lurk there also.

They say a stellar companion could explain the nebula’s shape, including its characteristic narrow waist and wide outflows.

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.

Stretching over the entirety of NIRCam’s field of view, these lobes are shown to be closed, bubble-like structures that each extend about 3 light-years. Outflowing gas from the centre of the nebula has inflated these massive bubbles over thousands of years.

Hairy

Dr Matsuura explained: “The legs are hairy and shine with molecular hydrogen emission, which have escaped from the torus.

“It is still unclear why the outflows appear ‘hairy’. One possibility is that the outflow from the primary star was not continuous, perhaps because mass transfer from the companion star affected the timing of the outflow.

“Another possibility is that the outflow interacted with the surrounding interstellar medium. Since the interstellar gas is not uniform to begin with, such interactions could cause the outflow to fragment, creating the hair-like structures along the legs.”

Gas is also actively jetting out from the nebula’s centre, in an elongated purple ‘S’ shape centred on the heart of the nebula.

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 team’s analysis, ‘JWST/NIRCam imaging of the Bipolar Planetary Nebula NGC 6537: the (Infra)red Spider, Revealed’, is published in The Astrophysical Journal.