How the iron bar formed is currently a mystery, the authors say. They will need further, more detailed observations to unravel what is going on. There are two potential scenarios: the iron bar may reveal something new about how the ejection of the nebula by the parent star progressed, or the iron might be an arc of plasma resulting from the vaporisation of particles of iron dust embedded in the Ring Nebula.
Co-author Professor Janet Drew, also based at UCL, advises caution: “We definitely need to know more – particularly whether any other chemical elements co-exist with the newly-detected iron, as this would probably tell us the right class of model to pursue. Right now, we are missing this important information.”
The team are working on a follow-up study, and plan to obtain data using WEAVE’s LIFU at higher spectral resolution to better understand how the bar might have formed.
WEAVE is carrying out eight surveys over the next five years, targeting everything from nearby white dwarfs to very distant galaxies. The Stellar, Circumstellar and Interstellar Physics strand of the WEAVE survey, led by Professor Drew, is observing many more ionized nebulae across the northern Milky Way.
“It would be very surprising if the iron bar in the Ring is unique,” explains Dr. Wesson. “So hopefully, as we observe and analyse more nebulae created in the same way, we will discover more examples of this phenomenon, which will help us to understand where the iron comes from.”
Professor Scott Trager, WEAVE Project Scientist based at the University of Groningen, added: “The discovery of this fascinating, previously unknown structure in a night-sky jewel, beloved by sky watchers across the Northern Hemisphere, demonstrates the amazing capabilities of WEAVE. We look forward to many more discoveries from this new instrument.”
This research paper was published in the Monthly Notices of the Royal Astronomical Society
Full title: WEAVE imaging spectroscopy of NGC 6720: an iron bar in the Ring
DOI: 10.1093/mnras/staf2139
URL: https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/staf2139
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