The disorderly death of a star, as observed by Webb

The messy death of a star

South Ring Nebula (NIRCam and MIRI images side by side). NASA’s James Webb Space Telescope offers dramatically different views of the South Ring Nebula. Each image combines near and mid-infrared light from three filters. On the left, Webb’s image of the South Ring Nebula highlights the very hot gas that surrounds the two central stars. On the right, Webb’s image traces the star’s scattered molecular outflows that have reached farther out into the cosmos. In the left image, blue and green have been assigned to Webb near-infrared data taken at 1.87 and 4.05 microns (F187N and F405N), and red has been assigned to data in the Webb’s mid-infrared taken at 18 microns (F1800W). In the right image, blue and green have been assigned to Webb’s near infrared data taken at 2.12 and 4.7 microns (F212N and F470N), and red has been assigned to Webb’s mid infrared data taken in 7.7 microns (F770W). Credit: NASA, ESA, CSA and O. De Marco (Macquarie University)

About 2,500 years ago, a star ejected most of its gas, forming the magnificent South Ring Nebula, NGC 3132, chosen as one of the first five image packets from the James Webb Space Telescope ( JWST).

A team of nearly 70 astronomers from 66 organizations across Europe, North, South and Central America and Asia used the JWST images to piece together the messy death of this star.

“It was almost three times the size of our sun, but much younger, about 500 million years old. It created envelopes of gas that expanded from the ejection site and left a remnant of dense white dwarf star, with about half the mass of the Sun, but approximately the size of the Earth,” says Professor Orsola De Marco, lead author of the paper, from the Center for Research in Astronomy, Astrophysics and Astrophotonics at Macquarie University.

“We were surprised to find evidence of two or three companion stars which likely hastened his death as well as another ‘innocent bystander’ star who got caught up in the interaction,” she says.

The study was based on JWST images supplemented with data from ESO’s Very Large Telescope in Chile, the San Pedro de Mártir Telescope in Mexico, the Gaia Space Telescope and the Hubble Space Telescope.

It paves the way for future JWST observations of nebulae, providing insight into fundamental astrophysical processes, including colliding winds and binary star interactions, with implications for supernovae and gravitational wave systems.

The article is published today in natural astronomy.

“When we first saw the images, we knew we had to do something, we had to investigate! The community came together and from this single image of a randomly chosen nebula, we were able to discern much more precise structures than ever before. The promise of the James Webb Space Telescope is incredible,” says De Marco, who is also chairman of the International Astronomical Union’s Commission on Planetary Nebulae.

Astronomers met online and developed theories and models around the mid-infrared image to reconstruct how dead the star was.

Shining at the center of the nebula is an ultra-hot central star, a white dwarf that has burned its own hydrogen. “This star is now small and hot, but is surrounded by cool dust,” said fellow team member Joel Kastner from the Rochester Institute of Technology USA. “We think all this gas and dust that we see thrown around must have come from this one star, but it was thrown in very specific directions by companion stars.”

There is also a series of spiral structures extending from the center. These concentric arcs would be created when a companion orbits the central star as it loses mass. Another companion is further away and is also visible in the photo.

Looking at a three-dimensional reconstruction of the data, the team also saw pairs of protrusions that can occur when astronomical objects ejects the material in the form of a jet. These are irregular and go in different directions, perhaps involving a triple star interaction in the center.

said DeMarco. “We first inferred the presence of a near companion because of the dusty disk around the central star, the additional partner that created the arches, and the super distant companion that you can see in the image. Once as we saw the jets, we knew there had to be another star or even two involved in the center, so we believe there are one or two very close companions, an additional mid-distance and a very distant one If so, there are four or even five objects involved in this messy death.”

More information:
Orsola De Marco, The disorderly death of a multiple star system and the resulting planetary nebula as observed by JWST, natural astronomy (2022). DOI: 10.1038/s41550-022-01845-2.

Quote: The Messy Death of a Star, as Observed by Webb (December 8, 2022) Retrieved December 9, 2022 from

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