September 15, 2025
Webb telescope finds clues to Earth’s creation in a cosmic butterfly
This image set shows three views of the Butterfly Nebula, also called NGC 6302. The first and second images highlight the bipolar nature of the Butterfly Nebula in optical and near-infrared light captured by the Hubble Space Telescope. The new Webb image on the right zooms in on the center of the nebula and its dusty torus. The Webb data are supplemented with data from the Atacama Large Millimeter/submillimeter Array, a powerful network of radio dishes.ESA/Webb, NASA & CSA, M. Matsuura, J. Kastner, K. Noll, ALMA (ESO/NAOJ/NRAO), N. Hirano, J. Kastner, M. Zamani (ESA/Webb)
The James Webb Space Telescope has revealed new details in the core of the Butterfly Nebula, known to astronomers as NGC 6302. From the dense ring of dust that surrounds the nebula’s core to the tiny but bright star hidden within, the Webb observations paint a never-before-seen portrait of the nebula’s inner workings. The new imagery also helps scientists understand the origins of comic dust.
“Most of the material in rocks, gems, bones — really the Earth itself — arrived here as a cloud of tiny cosmic dust particles. Rocky planets are made of this stuff,” said Bruce Balick, a UW professor emeritus of astronomy and a member of the research team. “The Butterfly Nebula is one of the nearest prolific sources of fresh cosmic dust, so it’s a great place to study how dust forms and disperses.”
The results were published Aug. 27 in Monthly Notices of the Royal Astronomical Society. The Webb telescope team published several images and extended captions on its mission website.
Planetary nebulae form when stars with masses between about 0.8 and eight times that of the sun shed most of their mass at the end of their lives, generating huge outbursts of gas and dust. The Butterfly Nebula, located about 3,400 light-years away in the constellation Scorpius, is one of the best-studied planetary nebulae in our galaxy and was previously imaged by the Hubble Space Telescope. It belongs to a class of bipolar nebulae, meaning that it has two lobes of dust and gas that spread out in opposite directions from the central star, forming the “wings” of the butterfly. The torus-shaped cloud of dust and gas poses as the butterfly’s “body” and obscures the star that created it.
This annotated image teases out the structures at the heart of the Butterfly Nebula. The James Webb Space Telescope’s MIRI instrument revealed many previously hidden aspects of the nebula.ESA/Webb, NASA & CSA, M. Matsuura, ALMA (ESO/NAOJ/NRAO), N. Hirano, M. Zamani (ESA/Webb)
The new Webb imagery zooms in on the center of the Butterfly Nebula and its dusty ring. The telescope’s uniquely powerful Mid-InfraRed Instrument, or MIRI, analyzed the chemical makeup of the dust and also peered through it, revealing the hidden star at the core. This Earth-sized star is tiny but over 1,000 times brighter than the sun, and at 222,000 Kelvin is one of the hottest known central stars in any planetary nebula.
Webb’s observations also revealed familiar materials in this exotic locale. The new data show that the dust ring is composed partly of crystalline silicates like quartz, which are common in rocks here on Earth. The team also spotted a class of organic molecules known as polycyclic aromatic hydrocarbons, or PAHs, which turn up in campfire smoke and burnt toast. This may be the first-ever evidence of PAHs forming in a planetary nebula, providing important clues to these molecules’ origin.
For researchers like Balick, getting a good look at both the central star and the dust it produced is key.
“Billions of long-gone stars, once similar to the newly discovered star that produced the Butterfly, created important raw materials like carbon-based organic molecules and silicates that condensed to make the Earth’s first surface,” Balick said. “The Butterfly enables us to look into the very start of this process.”
An image of the Butterfly Nebula taken by the Hubble Space Telescope at near-infrared wavelengths.ESA/Webb, NASA & CSA, J. Kastner, M. Zamani (ESA/Webb)
Contrary to the name, planetary nebulae have nothing to do with planets: The naming confusion began several hundred years ago, when astronomers reported that the first nebulae they found appeared round, like planets. The name stuck, even though many planetary nebulae aren’t round at all — the Butterfly Nebula itself is a prime example of the unusual and mysterious shapes that they can take.
“When I saw the new images, I realized there’s still a lot to learn about the formation and shaping of planetary nebulae — more than we ever anticipated,” Balick said. “But that’s how science works. You peel the onion one layer at a time.”
A full list of co-authors is included with the paper.
This research was funded by NASA and the European Space Agency (ESA), who funded the James Webb Space Telescope and its scientific instruments, as well as individual research grants from the teams’ home countries.
For more information, contact Balick at balick@uw.edu.
This story was adapted from a press release by NASA and ESA. See related post from the Royal Astronomical Society.
Tag(s): Bruce Balick • College of Arts & Sciences • Department of Astronomy • James Webb Space Telescope