Webb discovers what’s behind Butterfly Nebula’s signature glow

Scientists were able to pinpoint the location of the Butterfly Nebula’s central star. This had not been done before.

The James Webb Space Telescope has unearthed new details at the core of the Butterfly Nebula – one of the best studied planetary nebulas in the Milky Way galaxy. These new observations paint a “never-before-seen” portrait of this beautiful stellar object, say scientists.

The Butterfly Nebula is located roughly 3,400 light-years away in the Scorpius constellation. Although it is called a “planetary” nebula, the term has nothing to do with planets. These names were first coined hundreds of years ago when astronomers reported that these nebulas looked to be round – like planets. Not to mention, the term is particularly unfit for the Butterfly Nebula, which most definitely does not look round.

Nevertheless, planetary nebulas are formed when stars with masses between 0.8 to 8 times the mass of the sun shed most of their mass at the end of their lives. They are considerably short-lived when compared to much of what exists in the universe, lasting only around 20,000 years.

The Butterfly Nebula is a bipolar nebula, meaning it has two lobes spreading out in opposite directions – forming the image of the wings of a butterfly. The body of the nebula is shaped like a doughnut, or a torus, which hides the nebula’s central star.

The Butterfly Nebula as seen in wavelengths of light visible to us. Image: ESA/Webb, NASA & CSA, K Noll, J Kastner, M Zamani (ESA/Webb)

The Webb’s new image zooms in at this centre using the Mid-InfraRed Instrument (MIRI). The camera is able to take images at many different wavelengths simultaneously, revealing how an object’s appearance changes at the various wavelengths.

Moreover, the research team supplemented the Webb observations with data from the Atacama Large Millimeter/submillimeter Array (ALMA).

The team was able to identify almost 200 spectral lines, each of which holds information about the atoms and molecules in the nebula. They were also able to pinpoint the location of the Butterfly Nebula’s central star, which had not been done before.

According to the scientists, the central star has a previously undetected dust cloud around it, making the cloud shine brightly at the mid-infrared wavelengths which the MIRI is capable of picking up. With a temperature of 220,000 Kelvin, this is one of the hottest known central stars in a planetary nebula in our galaxy. The hot stellar engine is responsible for the nebula’s memorable glow.

Another interesting find from Webb is light emitted by carbon-based molecules known as polycyclic aromatic hydrocarbons (PAHs).

On Earth, PAHs are often found from campfire smoke, car exhausts or burnt toast. According to the scientists, this may be the first-ever evidence of PAHs forming in an oxygen-rich planetary nebula.

Earlier this month, a study led by the University of St Andrews using the James Webb found some evidence to suggest that free-floating planets could make their own miniature planetary systems without needing a star to orbit around.

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