About 2,500 years ago, a star ejected most of its gas, forming the Southern Ring Nebula, NGC 3132.
A team of nearly 70 astronomers from 66 organizations in Europe, North America, South and Central America, and Asia used images from the James Webb Space Telescope (JWST) to reconstruct 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 dense white dwarf star with about half the mass of the Sun but roughly the size of Earth,” says Professor Orsola De Marco, lead author of the paper, from Macquarie University Astronomy and Astrophysics Research Center in Sydney, Australia.
“We were surprised to find evidence of two or three companion stars that probably hastened its death, as well as one more innocent bystander star that was caught up in the interaction,” says De Marco.
The star ejected its gas, forming the Southern Ring Nebula
The study was based on JWST images, supplemented by data from the ESO Very Large Telescope in Chile, the San Pedro de Mártir Telescope in Mexico, the Gaia Space Telescope and the Hubble Space Telescope.
The work is published in Nature Astronomy.
“When I first saw the images, I knew we had to do something, we had to investigate! Thus, 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,” said De Marco, who is also chair of the International Astronomical Union Commission on Planetary Nebulae.
Astronomers have developed theories and models around the infrared image to reconstruct exactly how the star died. At the center of the nebula shines an ultra-hot central star, a white dwarf that has burned through its hydrogen.
“This star is now small and hot, but surrounded by cold dust,” said Joel Kastner, another member of the team, from the Rochester Institute of Technology in the US.
How many cosmic objects are involved in the messy death?
“We think that all that gas and dust that we see thrown around must have come from that one star, but it was thrown in very specific directions by the companion stars.”
There are also a series of spiral structures radiating from the center. These concentric arcs would have been created when a companion star orbits the central star as it loses mass. Another companion is further away and is also visible in the image.
Looking at a three-dimensional reconstruction of the data, the team also saw trails that can appear when astronomical objects eject matter in the form of jets. These are irregular and go out in different directions, which may imply an interaction with a triple star in the center, he writes Phys.org.
“We first inferred the presence of a close companion due to the dusty disk around the central star, the more distant companion that created the arcs, and the super distant companion. Once we saw the jets, we knew there had to be another star or even two involved in the center, so we think there are one or two very close companions, an additional mid-range one, and one very distant one. If this is the case, there are four or even five objects involved in this messy death,” explained De Marco.