Secrets of the Butterfly Nebula uncovered by Webb

Today’s Image of the Day from the European Space Agency features the Butterfly Nebula, located about 3,400 light-years away in the constellation Scorpius. 

It’s what astronomers call a planetary nebula – the brief phase when a dying star sheds its outer layers into space.

Despite the name, planetary nebulae have nothing to do with planets. Early astronomers thought these glowing shells looked round, like distant worlds seen through primitive telescopes. 

The name stuck, even though many nebulae are anything but round. The Butterfly Nebula, with its outstretched “wings” of gas and dust, is a perfect example.

Butterfly with a hidden heart

At the center of this spectacular cloud lies the remnant of a Sun-like star. It has burned through its fuel and shed most of its mass, leaving behind a blazing hot core. 

The star energizes the nebula, making it glow across the spectrum. Yet until recently, the star itself remained hidden.

A dark band of dust and gas cuts through the nebula like the “body” of the butterfly. This band is actually a torus, a doughnut-shaped structure that blocks visible light. 

The torus shapes the nebula by forcing gas outward in two opposite directions, creating the iconic bipolar wings. It also conceals the central star from optical view.

Webb telescope brings clarity

The James Webb Space Telescope has now pierced the dust with its Mid-Infrared Instrument, offering the sharpest view yet of the nebula’s core. 

By working in “integral field unit mode,” Webb captured images and spectra at multiple wavelengths simultaneously. The result is a detailed portrait of how the nebula looks in different slices of light.

The team also added data from the Atacama Large Millimeter/submillimeter Array in Chile, which revealed colder gas and dust. 

Together, these instruments exposed a structure of extraordinary complexity, with nearly 200 spectral lines tracing atoms and molecules woven into layered shells.

The central star revealed

The Webb observations finally pinned down the location of the nebula’s hidden star. Its surrounding dust cloud glows brightly in mid-infrared light, betraying its position for the first time. 

With a scorching temperature of 220,000 Kelvin – around 400,000 degrees Fahrenheit – this is one of the hottest known central stars in a planetary nebula.

That heat drives the nebula’s glow, but its power doesn’t escape evenly. The dense torus channels the outflow, creating the striking wings that stretch across space. 

Webb data show that the torus contains crystalline silicates such as quartz, along with irregular grains about a millionth of a meter across. For cosmic dust, that’s relatively large, suggesting the particles have been accumulating for a long time.

Jets, layers, and chemical signatures

Outside the torus, the nebula displays a multilayered design. Atoms that need the most energy to ionize cluster near the center. Those requiring less energy appear farther out. 

Among the highlights are iron and nickel, which mark out two jets blasting away from the star in opposite directions. These fast-moving streams help sculpt the overall shape of the nebula.

The team also found evidence of carbon-based molecules known as polycyclic aromatic hydrocarbons, or PAHs. 

On Earth, PAHs are common in soot from fires, exhaust fumes, and even burnt toast. In the Butterfly Nebula, they appear to form when bursts of stellar wind collide with the surrounding gas. 

This could be the first time PAHs have been spotted forming in an oxygen-rich planetary nebula, offering a rare window into the chemistry of dying stars.

Fleeting beauty of the Butterfly Nebula

The entire spectacle will not last long by cosmic standards. The planetary nebula stage endures only about 20,000 years – a brief flicker compared to a star’s lifetime of billions of years. 

The Butterfly Nebula is a reminder of how short-lived and yet astonishingly beautiful the final chapters of stellar evolution can be.

The results of this study are published in the Monthly Notices of the Royal Astronomical Society. 

The research shows that even well-studied objects like the Butterfly Nebula can surprise us when viewed with fresh eyes. 

Webb’s infrared vision has revealed not only the hidden star at the heart of the butterfly, but also the intricate chemistry that surrounds it – from crystalline dust to unexpected organic molecules.

Image Credit: ESA/Webb, NASA & CSA, J. Kastner, M. Zamani (ESA/Webb)

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–