Scientists have uncovered the clearest evidence yet of how cosmic dust is formed in space.
The process, which lays the foundations for rocky planets and contains ingredients linked to the origins of life, was captured by the James Webb Space Telescope (JWST).
Thought to be similar to rocks and sand on Earth, cosmic dust is made up of microscopic particles of minerals and organic material.
Much of this material has a randomly oriented-atomic structure like soot, but some of it forms beautiful, crystalline shapes like tiny gemstones.
For years, scientists have debated how this dust forms in space.
Now, a team of scientists led by Cardiff University, has confirmed these crystals form in a thick disk or torus of gas and dust that surrounds dying stars.
Their findings, presented in the journal Monthly Notices of Royal Astronomical Society, reveal how stars give rise to space dust, organic material, and the building blocks that rocky planets like Earth are made of.
Lead author Dr Mikako Matsuura of Cardiff University's School of Physics and Astronomy, said: "The observations show crystalline dust, mostly in the torus, but also some blowing away in the strong outflowing jets of gas."
This tells us the crystals likely formed in the torus, which is a dense, stable environment that formed from the ejected material from the star several thousand years ago. From this we can learn about stars in their current state and when they die.
Astronomy Group
Cardiff Hub for Astrophysics Research and Technology
The observations are of NGC 6302, a planetary nebula created by a dying star located in the Scorpius constellation, approximately 3,500 light years from Earth.
Previously captured by the Hubble Space Telescope, NGC 6302 is known as the Butterfly Nebula because of its two lobes that spread in opposite directions forming 'wings' and a 'body' of gas and dust which appears as a dark band at its centre.
JWST zoomed in on this dusty core of the Butterfly Nebula, providing the team of astronomers with an unprecedented view of its complex structure.
Co-author Dr Roger Wesson, also from Cardiff Univeristy's School of Physics and Astronomy, added: "The Butterfly Nebula is an incredibly complex object that still holds many mysteries, but JWST allows us to see things that even Hubble could not detect."
The dust formation revealed by these amazing new JWST observations provides clues as to how rocky planets like Earth may have formed around young stars. These findings are helping to reveal the lifecycles of planets, stars and dust within the cosmos.
Polycyclic aromatic hydrocarbons (PAHs)—complex carbon-based compounds also found in crude oil on Earth—were detected on the surface of the torus, where ultraviolet light from the star heats up the gas and dust.
PAHs were also seen at the edges of gas bubbles formed by bursts from the star.
"Unlike the crystalline silicates that form in calm conditions, PAHs seem to show up in more energetic, chaotic areas," explains Dr Matsuura, a Reader in the Cardiff Hub for Astrophysics Research and Technology.
We were surprised at just how dynamic the nebula is. The typical assumption is that planetary nebulae exist in a state of inactivity, a sort of resting phase for material which was ejected before the star became this shiny butterfly-like nebula. Instead, we see what resemble both cool gemstones formed in calm, long-lasting zones and fiery grime created in violent, fast-moving parts of space, all within a single object.
The latest observations use data from JWST's Mid-InfraRed Instrument (MIRI) working in integral field unit mode.
This mode combines a camera and a spectrograph to take images at many different wavelengths simultaneously, revealing how crystalline and organic dust appear in different wavelengths and locations.
Their paper, ' The JWST/MIRI view of the planetary nebula NGC 6302 I.: a UV irradiated torus and a hot bubble triggering PAH formation ' is published in Monthly Notices of Royal Astronomical Society.
