Utilizing the William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE), a sophisticated new instrument situated on the William Herschel Telescope at La Palma, astronomers have identified an unanticipated, elongated formation of ionized iron within the renowned Ring Nebula.
A composite image of the Ring Nebula constructed from four WEAVE/LIFU emission-line images. Image credit: Wesson et al., doi: 10.1093/mnras/staf2139.
The Ring Nebula, an emblematic example of a planetary nebula, resides approximately 2 stellar millennia distant within the constellation Lyra.
Also cataloged as Messier 57, M57, or NGC 6720, this celestial spectacle was first documented by the French astronomer Charles Messier during his comet-hunting endeavors in January of 1779.
The communication of Messier’s independent observation of Comet Bode reached the French astronomer Antoine Darquier de Pellepoix a fortnight thereafter. Subsequently, de Pellepoix independently rediscovered the Ring Nebula while tracking the aforementioned comet.
The recently ascertained bar-shaped agglomeration of iron atoms is situated within the inner periphery of the nebula’s elliptical configuration.
This agglomeration’s longitudinal dimension approximates 500 times the orbital radius of Pluto around the Sun, and its mass of iron atoms is roughly commensurate with the mass of the planet Mars.
The discovery of this formation was made through observations acquired via the Large Integral Field Unit (LIFU) operational mode of the novel WEAVE instrument attached to the Isaac Newton Group’s 4.2-meter William Herschel Telescope.
“Despite extensive prior investigation of the Ring Nebula utilizing a multitude of telescopes and instruments, WEAVE has afforded us a novel perspective, revealing unprecedented levels of detail,” stated Dr. Roger Wesson, an astrophysicist affiliated with University College London and Cardiff University.
“By capturing spectral data continuously across the entire expanse of the nebula, we possess the capability to generate imagery at any specific wavelength and ascertain its elemental composition at any given location.”
“Upon processing the data and reviewing the resulting imagery, a single feature emerged with striking clarity—this hitherto undetected ‘bar’ of ionized iron atoms, positioned centrally within the familiar and iconic ring structure.”
The precise nature of this iron ‘bar’ within the Ring Nebula remains indeterminate.
Two plausible hypotheses exist: the bar might elucidate novel insights into the process by which the parent star ejected the nebula, or, more compellingly, the iron could represent an arc of plasma resulting from the disintegration of a rocky planet that was engulfed during the star’s earlier phase of expansion.
“Further investigation is unequivocally warranted, particularly concerning the potential co-existence of other elemental substances with the newly identified iron, as such information would likely guide us toward the appropriate theoretical framework,” commented Professor Janet Drew, an astrophysicist at University College London.
“Currently, this critical piece of interpretive data is absent.”
These groundbreaking discoveries have been disseminated today in the esteemed publication, the Monthly Notices of the Royal Astronomical Society.
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R. Wesson et al. 2026. WEAVE imaging spectroscopy of NGC 6720: an iron bar in the Ring. MNRAS 546 (1): staf2139; doi: 10.1093/mnras/staf2139
