Thanks to the NASA/ESA/CSA James Webb Space Telescope, astronomers have made significant progress in understanding the connection between the raw materials of rocky planets. This cosmic material—crystalline silicate dust and polycyclic aromatic hydrocarbons—was analyzed in the core of the remarkable bipolar planetary nebula known as the Butterfly Nebula.

The Butterfly Nebula, also referred to as NGC 6302, is among the most extensively studied planetary nebulae.

This nebula is situated approximately 2,417 light years away from Earth, in the constellation Scorpio.

Its distinctive butterfly shape has expanded over two light years, roughly half the distance from the Sun to Proxima Centauri.

The object exhibits extreme bipolarity, complex morphology, and features very high excitation gases, high molecular weight, and crystalline silicates.

“The planetary nebula is one of the most stunning and elusive phenomena in the cosmic landscape,” stated Mikako, an astronomer from Cardiff University, along with Matsui Ko and her colleague.

“These nebulae form when stars with masses between 0.8 and 8 times that of the Sun shed most of their mass at the end of their lifecycle.”

“The nebula phases on planets are transient, lasting only about 20,000 years.”

“Despite their name, planetary nebulae have no connection to planets. The confusion arose centuries ago, when astronomers noted that these nebulae appeared round, resembling planets.”

“Although many planetary nebulae are not round, their titles often reflect misleading names, and the Butterfly Nebula is a prime illustration of the extraordinary shapes these nebulae can assume.”

“As a bipolar nebula, the Butterfly Nebula has two lobes extending in opposite directions, forming what resembles butterfly ‘wings’,” they continued.

“The dark band of dusty gas acts as the ‘body’ of the butterfly. This band is actually a donut-shaped torus that conceals the central star of the nebula.”

“Dusty donuts may indeed contribute to the insect-like shape of the nebula by hindering gas from escaping outward from the star uniformly.”

New images from Webb’s Mid-Infrared Instrument (MIRI) offer a close-up view of the center of the Butterfly Nebula and its dusty torus, revealing its complex structure like never before.

Astronomers have detected nearly 200 spectral lines, each providing insights into the nebula’s atoms and molecules.

These lines uncover nested interconnected structures tracked by various species.

Researchers have also pinpointed the central star in the Butterfly Nebula, which heats a previously undetected dust cloud surrounding it, causing it to emit bright light at mid-infrared wavelengths.

The star boasts a temperature of 220,000 Kelvin, making it one of the hottest known central stars in the galaxy’s planetary nebulae.

This image takes viewers diving deep into the heart of the Butterfly Nebula, as seen by Webb. Image credit: NASA/ESA/CSA/WEBB/M. MATSUURA/ALMA/ESO/NAOJ/NRAO/N. HIRANO/M. ZAMANI.

“This incredible, radiant engine is responsible for the stunning brilliance of the nebula, yet its full effect is moderated by the dense band of thin gas, the torus, that surrounds it,” the author noted.

“New data from Webb reveals that the torus comprises crystalline silicates such as quartz and irregularly shaped dust particles.”

“Dust grains measure about one millionth of a meter, typical for space dust.”

“Beyond the torus, emissions from various atoms and molecules form multilayer structures.”

“Ions needing the highest energy to form cluster near the center, while those requiring less energy are positioned farther away from the central star.”

“Iron and nickel are particularly noteworthy, following jets that erupt outward from the star in opposite directions.”

In an intriguing finding, the team also identified light emitted by carbon-based molecules known as polycyclic aromatic hydrocarbons (PAHs).

“These molecules have a flat, ring-like configuration, reminiscent of honeycomb shapes found in beehives,” said the astronomer.

“On Earth, PAHs are often present in smoke from campfires, vehicle exhausts, or burnt toast.”

“Given their location, these PAHs likely form when the winds from the central star push against the surrounding gas.”

“This discovery marks the first evidence of PAH formation in oxygen-rich planetary nebulae, offering a glimpse into the processes behind their formation.”

Survey results were published this week in the Monthly Notices of the Royal Astronomical Society.

____

Mikako Matsumura et al. 2025. JWST/MIRI view of Planetary Nebula NGC 6302 – I. UV irradiated torus and hot bubbles cause PAH formation. mnras 542(2):1287-1307; doi:10.1093/mnras/staf1194