Inside the Butterfly Nebula
a deeper portrait of one of the most complex nebulae
Stunning images from the James Webb Telescope show a dying nebula 3,400 light years away from Earth and reveal an astronomical cauldron roiling with ash, dust, and gasses, according to a new report by Senior Research Scientist Kathleen Kraemer of AV研究所鈥檚 Institute for Scientific Research and an international team of scientists.
The findings, published this month in Monthly Notices of the Royal Astronomical Society, unveil many new discoveries and a deeper portrait of the nebula, the star at its center鈥攑reviously obscured by a dusty halo鈥攁nd flowing strands of burning gasses.
Data examined by Kraemer and other researchers led by Mikako Matsuura, of the University of Cardiff, come from images and electromagnetic wave measurements produced by the $10-billion James Webb Space Telescope, which was focused on what is known as Butterfly Nebula, NGC 6302.
鈥淪ince this was a new instrument, we had no idea how much detail we would be getting from this data,鈥� said Kraemer, an astrophysicist who specializes in dying stars. 鈥淚t鈥檚 spectacular. We are drinking from a fire hose here. We will be talking to the modelers and the people in the lab, because we are seeing features we have not seen before. That鈥檚 part of the fun鈥攆inding things you did not expect and don鈥檛 yet know what they are.鈥�
![This image set showcases three views of the Butterfly Nebula, also called NGC 6302. The Butterfly Nebula, located about 3400 light-years away in the constellation Scorpius, is one of the best-studied planetary nebulae in our galaxy. 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. The Butterfly Nebula is a bipolar nebula, meaning that it has two lobes that spread in opposite directions, forming the 鈥榳ings鈥� of the butterfly. A dark band of dusty gas poses as the butterfly鈥檚 鈥榖ody鈥�. This band is actually a doughnut-shaped torus that鈥檚 being viewed from the side, hiding the nebula鈥檚 central star 鈥� the ancient core of a Sun-like star that energises the nebula and causes it to glow. The dusty doughnut may be responsible for the nebula鈥檚 insectoid shape by preventing gas from flowing outward from the star equally in all directions.听 The first and second of the three images shown here highlight the bipolar nature of the Butterfly Nebula in optical and near-infrared light captured by the NASA/ESA Hubble Space Telescope. The new Webb image on the right zooms in on the centre of the Butterfly Nebula and its dusty torus, providing an unprecedented view of its complex structure. The Webb data are supplemented with data from the Atacama Large Millimetre/submillimetre Array, a powerful network of radio dishes.听 While the nebula鈥檚 central star is blanketed with thick, dusty gas at optical wavelengths, Webb鈥檚 infrared capabilities reveal the central star and show the doughnut-shaped torus and interconnected bubbles of dusty gas that surround it. [Image description: Three views of the same nebula, presented side by side. The left and middle images, which are labeled 鈥楬ubble Optical鈥� and 鈥楬ubble Near IR鈥�, 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 鈥榃ebb & ALMA, Mid-IR & Sub-mm鈥�. 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.]](/content/dam/bc1/sites/bc-news/2025/fall/nasa-butterfly/Butterfly_Nebula_NGC_6302.jpg "Butterfly Nebula NGC 6302 (Hubble and Webb + ALMA images, side by side)")
This image set showcases three views of the Butterfly Nebula, also called NGC 6302. The Butterfly Nebula, located about 3400 light-years away in the constellation Scorpius, is one of the best-studied planetary nebulae in our galaxy. CREDIT ESA/Webb, NASA & CSA, M. Matsuura, J. Kastner, K. Noll, ALMA (ESO/NAOJ/NRAO), N. Hirano, J. Kastner, M. Zamani (ESA/Webb)
With funding from NASA, Kraemer has been working on the project for nearly four years and has spent the past 18 months parsing the data and images returned by the telescope, which was launched into space in 2021. Her specialization of infrared astronomy uses data from infrared radiation to examine the physical properties of extraterrestrial sources such as the nebula鈥攊n this case dust and gas shed by the dying star.
The Butterfly Nebula is located approximately 3,400 light-years away from Earth in the constellation Scorpius. For perspective, the sun is a mere eight light minutes away from the Earth. The nebula has been studied extensively and previously imaged by the Hubble Space Telescope, the pioneering predecessor to Webb.听
According to the European Space Agency, a central Webb partner, the new images 鈥渮oom in on the centre of the Butterfly Nebula and its dusty torus, providing an unprecedented view of its complex structure.鈥� The research team supplemented the Webb observations with data from the Atacama Large Millimeter/submillimeter Array (ALMA), a powerful network of radio dishes.
鈥淥ur task is to interpret the data and determine what these different structures we see mean,鈥� said Kraemer. 鈥淲e鈥檙e interpreting the different materials the star is ejecting. Some colors trace material that is kind of like soot. Other colors trace where a lot of silicon dust is flowing. Other colors are hot gases. All of that is being ejected back into space and will ultimately be recycled into new stars and planets some day.鈥�
“We wanted to know what was going on in the core of the nebula. Data from the Hubble telescope showed the center of the nebula was blocked by clouds of dust. Now we know more about what is going on in the core and causing the larger structures...We are excited to keep digging into the [Webb] data.”
Kraemer鈥檚 interest in astronomy was piqued as a child by spending evenings with her father looking at the stars in the backyard of their home near an Air Force base in Southern California. That led her to Caltech as an undergraduate, and a PhD at Boston University. As a scientist, she finds dying stars the most interesting.
鈥淭here are people who like middle-aged stars, but I think the dying ones are much more interesting,鈥� she said. 鈥淭his is where they are ejecting their materials back into space where they end up in new stars and planets.鈥�
The carbon thrown off across millennia not only replenishes the galaxy, but ends up in each one of us, she noted.
鈥淭he carbon in us was mostly produced by nebulas,鈥� she said.
Among the key findings is the source of the cast off soot and dust 鈥� which in the case of the Butterfly Nebula creates a torus, or a donut-shaped feature of dust and gas that surrounds the center of the star, Kraemer said.
鈥淲e wanted to know what was going on in the core of the nebula,鈥� said Kraemer. 鈥淒ata from the Hubble telescope showed the center of the nebula was blocked by clouds of dust. Now we know more about what is going on in the core and causing the larger structures.鈥�
As the star dies, she said, 鈥渓ight is being shot out in directions perpendicular to the torus and that makes the butterfly shape.鈥�
In this cauldron of soot, sand, and gas, the images are informing what is known about the chemistry at play, the radiation at the core of the nebula, the molecules that can be formed and the temperatures they reach, Kraemer said.
Kraemer is already looking forward to the next phases of the project exploring additional data from the Webb telescope and seeing what more they reveal.听
She added, 鈥淲e are excited to keep digging into the data.鈥�
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