NASA’s James Webb Space Telescope spotted two rare kinds of dust in the dwarf galaxy Sextans A, offering insights into how early galaxies evolved and developed the building blocks for planets. Scientists found metallic iron dust and silicon carbide (SiC) being produced by ageing stars. The finding shows that even when very little of today’s heavy elements were present, stars and the interstellar medium could still create solid dust grains. Sextans A is approximately 4 million light-years away, and its gravitational pull is so weak that it is unable to retain the heavy elements, such as iron and oxygen, created by supernovae and ageing stars. Galaxies like these filled the early universe. With low metal content, the stars in them should be dust-free. “Instead, Webb revealed a star forging dust grains made almost entirely of iron. This is something we’ve never seen in stars that are analogues of stars in the early universe,” Martha Boyer, lead author in one of the companion studies, said.
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