One of the most photographed images in the night sky comes into focus for the first time
NASA/ESA/O'Dell/Ferland/Henney/Peimbert/Thompson; SMA image and SMA/JWST image overlay: Joel Kastner/RIT
The Ring Nebula as captured in visible light by Hubble Space Telescope, left; in radio emission from CO molecules by the Submillimeter Array (SMA), center; and in the infrared by the James Webb Space Telescope (JWST), right. The image is overlaid with contours of emission from CO that is moving perpendicular to our sight line, showing how the molecular gas imaged by the SMA envelopes the ionized gas imaged by JWST.
The Ring Nebula is perhaps one of the most photographed objects in the night sky, dating back to its first image in 1886. Its intrinsic structure has been debated for as long as it has been observed.
Scientists now have obtained the clearest three-dimensional view of the nebula, thanks to a research team led by Rochester Institute of Technology Chester F. Carlson Center for Imaging Science and School of Physics and Astronomy Professor Joel Kastner.
The team determined the nebula to have an ellipsoidal shape using Submillimeter Array (SMA) radio-wavelength mapping of emission from carbon monoxide (CO) gas. The CO emission reveals cold, molecular gas that envelopes the hot gas and dust seen in images of the nebula obtained by the Hubble Space Telescope (HST) and, more recently, the James Webb Space Telescope (JWST).
"We looked at the data and the ellipsoidal structure was obvious, so we could put together a simple geometrical model. Now, we understand the structure of this nebula," said Kastner. "The James Webb Space Telescope gives us a collapsed image of what the object looks like in the sky. The SMA allows us to accurately measure the velocities of the molecular gas in the nebula, so we can see what's moving toward or away from us."
Astronomers have theorized that the nebula is ring-shaped or has a soap bubble structure, but the model created from the SMA data revealed it is an ellipsoid. The SMA data pinpoint the velocities and locations of the carbon dioxide molecules ejected by the dying star that generated the Ring Nebula and reveal its 3D shape, which can't be inferred from telescopic images, even using powerful NASA space observatories like HST and JWST.
The modeling allowed the astronomers to estimate that roughly 6,000 years have elapsed since the dying star, then a red giant, ejected the molecular gas that envelopes the nebula. The SMA data also reveal telltale signatures of the influence of a companion star to the former red giant at the center of the nebula, in the form of high-velocity blobs of gas that appear to have popped out of each end of the ellipsoidal shell.
These findings follow similar research done on the Southern Ring Nebula, one of the first objects observed by the JWST. Kastner and his team authored a paper reporting a deeper understanding of the Southern Ring's structure in the spring of 2024. This new approach of using the combination of SMA mapping and JWST imaging to tease out the 3D structures of these objects gives scientists a fresh way to understand the final, dying stages of sun-like stars.
“The stars that generate planetary nebulae like the Ring and Southern Ring may have produced much of the carbon in the universe,” said Kastner. “We can watch that carbon on its way to being recycled into the next generation of stars and planets when we observe these amazing objects.”
Kastner is the lead author of a paper on this new 3D view of the Ring Nebula that is about to be submitted to The Astrophysical Journal. The research team included RIT astrophysical sciences and technology graduate students Diana Ryder and Paula Moraga Baez, who just received her Ph.D. in fall 2024). Other co-authors are David Wilner (Center for Astrophysics, Harvard & Smithsonian); Orsola De Marco (Macquarie University, Australia); Raghvendra Sahai (Jet Propulsion Laboratory); Al Wootten (National Radio Astronomy Observatory); and Albert Zijlstra (University of Manchester, UK). Kastner's research on molecular gas in planetary nebulae is supported by a grant from the National Science Foundation.
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