When the James Webb Space Telescope (Webb) revealed unprecedented details of the Butterfly Nebula's intricate heart, Western University researchers made discoveries that transform our understanding of cosmic chemistry - finding molecules where they shouldn't exist and uncovering clues about how complex carbon structures form in space.
The stunning images and data released today by the European Space Agency (ESA) show the mesmerizing structures within the Butterfly Nebula (NGC 6302), located 3,400 light-years away. But for Western's team, those beautiful, complex shapes represent something more: chemical laboratories where unexpected molecular processes are reshaping our knowledge of stellar environments.
Jan Cami
"What's remarkable is how Webb lets us use chemistry as a detective tool," said Western physics and astronomy professor Jan Cami. "When we see unexpected molecules or unusual molecular behaviour, it tells us something fundamental about the physical processes shaping these stunning structures. Each chemical signature is like a fingerprint of what is happening in that region."
The Butterfly Nebula, located in the constellation Scorpius, is one of the best-studied planetary nebulae in our galaxy. This stunning nebula was previously imaged by the NASA/ESA Hubble Space Telescope. Now, Webb has captured a new view.
The new images and discoveries were published today in Monthly Notices of the Royal Astronomical Society.
Planetary nebulae are among the most beautiful and most elusive creatures in the cosmic zoo. These nebulae form when stars with masses between about 0.8 and 8 times the mass of the Sun shed most of their mass at the end of their lives. The planetary nebula phase is fleeting, lasting only about 20,000 years.
Contrary to the name, planetary nebulae have nothing to do with planets: the naming confusion began several hundred years ago, when astronomers reported that these nebulae appeared round, like planets. The name stuck, even though many planetary nebulae aren't round at all - and the Butterfly Nebula is a prime example of the fantastic shapes that these nebulae can take.
The Butterfly Nebula is a bipolar nebula, meaning that it has two lobes that spread in opposite directions, forming the 'wings' of the butterfly. A dark band of dusty gas poses as the butterfly's 'body'. This band is actually a doughnut-shaped torus that's being viewed from the side, hiding the nebula's central star - the ancient core of a Sun-like star that energizes the nebula and causes it to glow. The dusty doughnut may be responsible for the nebula's insectoid shape by preventing gas from flowing outward from the star equally in all directions.
Cami, physics and astronomy professor Els Peeters, and graduate students Charmi Bhatt and Nicholas Clark, all affiliated with Western's Institute for Earth and Space Exploration, collaborated with researchers from the United Kingdom, United States and France on this most recent Webb study.
Three views of the same nebula, presented side by side. The left and middle images, which are labeled 'Hubble Optical' and 'Hubble Near IR', show the nebula at roughly the same scale. These two images show some similar features, including a dark dust lane that runs through the centre of the nebula and two broad clouds that emerge from either side of the dust lane like the outstretched wings of a butterfly. A diamond-shaped region centred on the dust lane is outlined in each of these images. In the optical Hubble image, the nebula appears clumpy and nearly opaque, with few background stars showing through the cloudy material. The nebula appears in different shades of cream, yellow and orange, with the lightest colours appearing closest to the centre. The background of space is black with a handful of stars that are tinged pink. In the near-infrared Hubble image, the nebula appears cream coloured and most opaque near the centre, then becomes reddish with purple streaks and more translucent out toward the wings of the nebula. There are hundreds of background stars in the image, many of which are visible through the nebula. The third and final image zooms in on the diamond-shaped region near the centre of the other two images. This image is labeled 'Webb & ALMA, Mid-IR & Sub-mm'. This image is completely different from the other two, showing a bright source at the centre that is surrounded by greenish nebulosity and several looping lines in cream, orange and pink. The upper-right and lower-left corners of this image show a purple streak pointing out of the image. Credit: ESA/Webb, NASA & CSA, M. Matsuura, J. Kastner, K. Noll, ALMA (ESO/NAOJ/NRAO), N. Hirano, J. Kastner, M. Zamani (ESA/Webb)
Surprising chemistry in a stellar graveyard
Using the new Webb images, Bhatt made a discovery that surprised even seasoned astronomers: the first detection of CH₃⁺ (methyl cation) in any planetary nebula. This carbon-containing molecule wasn't expected to survive in the oxygen-rich environment surrounding the dying star.
"Using the James Webb Space Telescope, we've detected CH₃⁺ in an environment where such carbon-containing molecules shouldn't exist," said Bhatt. "But we soon realized that intense UV radiation from the central star - one of the hottest known in our galaxy at 220,000 degrees Kelvin - fundamentally changes the chemistry that can occur."
The discovery reveals new possibilities for complex chemistry in space, potentially expanding our understanding of the diverse environments where carbon-based molecules can form.
"When I think about all the chemistry that CH₃⁺ can trigger, I get genuinely excited," said Bhatt. "This molecule is like a key that unlocks an entire chemical network we didn't know was possible in oxygen-rich stellar environments - and with Webb's capabilities, we're just beginning to explore what this means."
Cosmic carbon factories
Intriguingly, the international team also spotted light emitted by carbon-based molecules known as polycyclic aromatic hydrocarbons, or PAHs. They form flat, ring-like structures, much like the honeycomb shapes found in beehives.
Again, using the new images, Clark investigated the PAHs and his detailed analysis revealed they're behaving in unprecedented ways within the Butterfly Nebula.
"In the Butterfly Nebula, we're seeing these molecules behave in unexpected ways - their emission varies dramatically across different regions, reflecting the nebula's complex physical conditions," said Clark. "Most exciting is that these PAHs appear to be forming right now in the nebula's harsh environment, rather than being inherited from earlier stellar phases."
This observation provides a rare window into one of astrophysics' enduring mysteries: how PAHs actually form.
"The formation of PAHs has been one of our field's most challenging puzzles," said Clark. "It's exciting that the Butterfly Nebula may hold the key to making progress in solving it."
While part of this study, Bhatt's CH₃⁺ detection and Clark's full PAH analysis will also be published independently and more in depth in the near future.
International collaboration powers discovery
The new breakthrough discoveries demonstrate the power of bringing together world-class expertise from around the globe. Western's team contributed their specialized knowledge of molecular spectroscopy and astrochemistry to an international collaboration studying Webb's observations.
Els Peeters
"These discoveries perfectly illustrate the power of international collaboration," said Peeters. "Our Western team brings expertise in molecular spectroscopy and astrochemistry, while our collaborators contribute their specialized knowledge of stellar physics and nebular dynamics. Together, we're able to decode Webb's observations in ways none of us could achieve alone."
The intricate structures Webb reveals aren't just beautiful - they're active chemical laboratories. Each region's unique physical conditions drive different chemical processes, and by detecting unexpected molecules like CH₃⁺ or unusual PAH emission patterns, researchers can work backwards to understand the physical processes creating these mesmerizing structures.
"It's a fascinating interplay where chemistry becomes our diagnostic tool for understanding stellar physics," said Peeters. "The same processes that create those stunning butterfly wings and complex nested structures also drive the chemistry we're detecting. We're essentially using molecules as messengers to tell us about the physics happening in regions too distant and extreme for us to study any other way."
Webb, a joint collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA), has proven to be a game-changer in astronomy. Its capabilities go beyond what was possible with previous space telescopes, allowing scientists to peer deeper into the cosmos and explore new frontiers of the universe. And as Webb continues to probe the cosmos, Western's molecular detective work promises to unlock more secrets hidden within the universe's most spectacular stellar displays.
"Being part of this international collaboration has been extraordinary. Webb's unprecedented capabilities combined with this collaborative approach is revealing cosmic chemistry we never imagined possible. It's incredibly exciting to be riding this wave of Webb discoveries as part of this global scientific effort," said Cami.
The complicated structure at the centre of the Butterfly Nebula, NGC 6302. There is a bright source at the centre of the image, labeled 'dying star'. This is surrounded by greenish nebulosity and several looping lines in cream, orange and pink. One of these lines appears to form a ring oriented vertically and nearly edge-on around the bright source at the centre. This ring is labeled in several different places to indicate the near and far sides of a structure called the torus, a dust lane running along the torus and an area where the torus is ionised. Other lines trace out a figure eight shape. These lines are labeled to indicate the inner bubble as well as where the bubble intersects with the torus. Moving outward from these complex lines and green nebulosity, there is a section of red light on either side of the object, labeled 'outer bubble'. The upper-right and lower-left corners of this image show a purple streak pointing out of the image. These purple streaks are labeled 'jet'. Credit: ESA/Webb, NASA & CSA, M. Matsuura, ALMA (ESO/NAOJ/NRAO), N. Hirano, M. Zamani (ESA/Webb)
