Editor’s Note: This article was co-written by Lucas Brown and Alexia Kubas, our 2026–2027 AAS Media Fellows. We’re excited to welcome Lucas and Alexia to the team and look forward to featuring their writing on AAS Nova regularly!

Planetary nebulae mark a key evolutionary phase for low- and intermediate-mass stars, but properties of the parent star are difficult to sleuth out. Researchers have discovered an extragalactic planetary nebula in the center of a star cluster, offering an unprecedented opportunity to trace planetary nebula properties to parent star stats.

The Puzzle of Planetary Nebula Progenitors

A planetary nebula, so named because the first ones discovered resemble the planet Uranus in a small telescope, forms when a Sun-like star runs out of fuel and sheds its outer layers, leaving a hot remnant core enveloped in a gaseous nebula. At higher masses, a different process kicks in: stellar cores can collapse to produce a chaotic burst of stellar material called a supernova. Where exactly the boundary should be placed between planetary nebula progenitors and supernova-forming stars remains an outstanding question in the field of stellar evolution.

Answering this question is challenging because once a planetary nebula becomes visible, the progenitor star’s transition into a hot, compact white dwarf is already underway, making it difficult to determine the star’s initial mass. For this task, researchers seek out planetary nebulae within open clusters — groups of stars that were born from the same molecular cloud and are roughly the same age — so that cluster characteristics can help piece together the progenitor puzzle. Since open clusters tend to be relatively young, they are also a great tool to probe planetary nebulae from more massive progenitors and explore the boundary between stars that produce planetary nebulae and those that go supernova.

Striking Gold

Numerous planetary nebula–open cluster pairs have been found in the Milky Way, but among those with well-constrained progenitor masses, very few push into the higher-mass regime where things get really interesting. Outside our home galaxy, the search has proven even more challenging due to data sparsity. Despite the odds, Pinjian Chen (Chinese Academy of Sciences) and collaborators have found a planetary nebula with one of the highest known progenitor masses in an open cluster in the Andromeda Galaxy.

To make this identification, Chen’s team used archival Hubble Space Telescope and MMT data to examine the location of the planetary nebula candidate M279 within the Andromeda Galaxy. The researchers’ critical observation was that the nebula not only overlaps with the position of an open star cluster called AP 210, but it also has an estimated velocity that matches the velocity of other stars in the cluster. These associations, when combined, provide strong evidence that M279 originated within the cluster.

What’s My (Cluster) Age Again?

M279’s cluster origin has significant consequences for pinning down the properties of the progenitor star. First, stars in open clusters all form at roughly the same time — 90 million years ago in the case of AP 210 — allowing the authors to set a tight constraint on the progenitor’s age. Then, because the rate at which a star burns through its nuclear fuel and generates a planetary nebula is related to its initial mass, the researchers are able to connect this age to a specific progenitor mass of around 5.7 solar masses.

The team also subtracted the central star’s contribution from the observed spectrum to isolate the nebula’s composition, illuminating specific nuclear processes relevant to higher-mass stars. Planetary nebulae are cosmic cocktails whose chemical abundances trace the composition of the interstellar medium when the progenitor formed as well as elements formed via nucleosynthesis inside the star during its lifetime. Chen and collaborators found the nebula to be significantly nitrogen-enhanced, which is consistent with a massive asymptotic giant branch progenitor undergoing hot bottom burning that converts carbon to nitrogen. This newly minted metal would then be mixed back into the star’s outer layers, flooding the resultant nebula with its particular spectral signature.

While this work represents only a single observation of a high-progenitor-mass planetary nebula — and only the third compelling extragalactic planetary nebula–open cluster pair — it opens up the possibility that there may be many more waiting to be found, unlocking new insight into the lives of massive stars.

Citation

“A Planetary Nebula from a 5.7 M_⊙ Progenitor in a 90 Myr M31 Star Cluster,” Pinjian Chen et al 2026 ApJL 1005 L2. doi:10.3847/2041-8213/ae77e4

The post Extragalactic Planetary Nebula with Massive Progenitor Sheds Light on Stellar Evolution appeared first on AAS Nova.

Observing across the starry “plains” of space, NASA’s James Webb Space Telescope has taken new images of NGC 2392, nicknamed the Lion Nebula. NASA’s Hubble Space Telescope previously viewed this planetary nebula in 2000, imaging the lion face-shaped target in visible light and revealing features such as the “mane” of hazy, comet-shaped objects. Now Webb has captured a clearer, more detailed view of the Lion Nebula due to its high-resolution imaging.

Lion Nebula (NIRCam and MIRI Image)

At first glance the nebula’s overall structure in Webb’s infrared images, with both the NIRCam (Near Infrared Camera) and MIRI (Mid Infrared Instrument) instruments, may look quite similar to Hubble’s earlier visible-light view. However, Webb’s infrared vision highlights features like compact clumps of dust and a haze of ionized gas. It’s taken several thousand years for this collection of gas and dust to reach its current shape, and the nebula’s components continue to be altered.

The source of these constant changes and the reason for the Lion Nebula’s distinct appearance is located at the center: the remains of a dying star. Though it looks like the button nose of the lion, its energy and radiation are powering the intricate structures seen here.

Lion Nebula (MIRI Image)

Massive stars undergo supernova explosions at the end of their lives, but these kinds of events are few and far in between. Most of the universe’s stars have lower masses, like the one belonging to NGC 2392. When a lower-mass star can no longer sustain itself with nuclear reactions in its core, the star becomes unstable and pulsates, losing its mass by shedding its outer layers, which then turn into shells of gas and dust called a planetary nebula. (Stars at this life stage are responsible for producing much of the universe’s observable dust.) The star’s radiation drives the ejected material away, leaving behind the very hot stellar core, also known as a white dwarf.

In the Lion Nebula’s case, the death of the oxygen-rich central star has left behind a white dwarf that is “cooking” everything from the inside and producing a bubble of ionized gas as it does. The gas bubble, which forms the lion’s face, is expanding over time and destroying dust that is in its path. Understanding why the swept-up gas has a complex structure of rings and shells, a common feature in planetary nebulae, is an ongoing endeavor.

The mane of the lion is the interior of a dust shell that is being illuminated by the white dwarf at the center. The tufts of hair, which look like cometary tails of material, are compact clumps of dust that have survived the stellar core’s radiation and protect the material that lies behind them.

Webb’s imagery “freezes” this planetary nebula in time, though the star’s death, and its tumultuous effects, go on. NGC 2392 will continue to undergo changes as its gas and dust migrate away from the stellar core. Astronomers estimate the lion will eventually disperse in approximately 10,000 years — a relatively short period in astronomical terms.

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

To learn more about Webb, visit:

https://science.nasa.gov/webb

Downloads & Related Information

The following sections contain links to download this article’s images and videos in all available resolutions followed by related information links, media contacts, and if available, research paper and Spanish translation links.

Related Links

Explore more: Sonification of NGC 2392

View more: Hubble Image of NGC 2392

View more: Chandra X-ray Observatory Image of NGC 2392

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Fullerenes — a class of molecules composed entirely of interconnected carbon atoms — are the largest molecules definitively detected in space. Researchers using JWST to study a planetary nebula have found new spectral features from a fullerene composed of 60 carbon atoms, offering another way to study how these molecules form and survive in space.

Full of Fullerenes

The planetary nebula Tc 1 holds special significance in the field of astrochemistry. More than a decade ago, researchers using the Spitzer Space Telescope studied this wispy nebula illuminated by the core of a dead star. These observations led to the first confident identification of molecules called fullerenes in space. Fullerenes are large molecules constructed from interconnected rings of carbon atoms, forming hollow spheres, rugby-ball shapes, and long tubes. Spheroidal fullerenes, especially C₆₀, are commonly referred to as buckyballs.

Since that discovery, Tc 1 has been a hot spot for studies of buckyballs. However, researchers are still puzzling over how these large molecules form and survive in harsh space environments.

From Spitzer to JWST

Morgan Giese (The University of Western Ontario) and collaborators recently reported on the results of a JWST observing program that aimed to understand how fullerenes respond to changes in their environment. The team mapped the distribution of C₆₀ molecules at varying distances from the powerful ionizing radiation of Tc 1’s central star.

The team successfully spotted the emission features from the fullerene C₆₀ seen in earlier observations, but they also turned up something unexpected: a handful of prominent emission features from 3.5 to 5.2 microns that had not been reported previously.

Feature Presentation

What’s the source of these emission features? The distribution of the emission provides a strong clue: known spectral features from fullerenes C₆₀ and C₇₀ are concentrated in a narrow, bright ring around the center of the nebula, with diffuse emission suffusing the rest of the nebula — and the newfound spectral features follow the same distribution.

This evidence hints that C₆₀ or C₇₀ is the source of these new features, but Giese’s team took the investigation a step further. Using anharmonic quantum chemical calculations, they computed the spectrum of C₆₀‘s combination bands, which arise when multiple vibrational modes are excited at the same time. This is the first time this type of spectrum has been calculated for C₆₀, and the authors found good agreement between their computed spectrum and the JWST spectrum, providing further evidence that C₆₀ is the source of these bands.

Giese and coauthors found that 17% of the energy emitted by the C₆₀ molecules in Tc 1 is released in these  combination bands, suggesting that these features must be taken into account when modeling the cooling of C₆₀ molecules. The discovery of new fullerene spectral features also has implications for future studies of these molecules: since these features appear in a wavelength range where features from other complex molecules like polycyclic aromatic hydrocarbons are weak, these newly identified bands provide a promising way to spot and study fullerenes across space environments.

Citation

“Detection of C₆₀ Combination Bands in the Near-IR Spectrum of Tc 1,” Morgan M. Giese et al 2026 ApJL 1004 L32. doi:10.3847/2041-8213/ae76d5

The post New Spectral Signs of Buckyballs Discovered in Planetary Nebula appeared first on AAS Nova.

The iconic and widely photographed Ring Nebula is one of the most recognizable planetary nebulae: short-lived, often brilliantly colored nebulae that form when low- to intermediate-mass stars shed their outer layers. The three images above show the central region of the Ring Nebula through the eyes of JWST’s Mid Infrared Instrument. The leftmost image clearly shows the Ring Nebula’s central star: a hot, crystallized stellar core called a white dwarf. In a recent research article, Raghvendra Sahai (Jet Propulsion Laboratory) and collaborators analyzed these JWST observations, leading to the discovery of a dusty disk around the Ring Nebula’s central star. This is just the second time that a resolved disk has been discovered around the central star of a planetary nebula. Disks with radii from 0.01 to 1,000 au have been found around evolved stars in the asymptotic giant branch phase through the planetary nebula phase, but it’s not yet clear how these disks form and how long they last. Most intriguingly, the presence of disks around highly evolved stars raises the possibility of a second phase of planet formation. To learn more about the JWST observations of the Ring Nebula, and what they tell us about the properties of the central star and its disk, be sure to check out the full research article linked below.

Citation

“JWST Observations of the Ring Nebula (NGC 6720). III. A Dusty Disk Around Its Central Star,” Raghvendra Sahai et al 2025 ApJ 985 101. doi:10.3847/1538-4357/adc91c

The post Featured Image: JWST Examines the Ring Nebula appeared first on AAS Nova.