Dust is the first solid matter formed, and investigating cosmic dust is a very active field within astrophysics. We cannot replicate the formation conditions of cosmic dust here on Earth exactly, and no single method of producing analogue dust samples in the laboratory can simulate all of the dust we observe around stars and in the interstellar medium. However, by creating and characterising these samples, and comparing them to astronomical data to see where they are similar, and where they differ, we increase our understanding of the formation, composition and evolution of their cosmic counterparts
The sol-gel process is a chemical method used to produce solid materials from small molecules. Sol-gels have a consistency similar to hand cream and must be dried to form the dust samples. Air-drying takes about 24 hours and is time-consuming for researchers who wish to produce multiple samples.
Another challenging aspect of producing analogue dust samples is the inclusion of iron, which - on Earth - tends to form rust (iron oxides) that isn't seen in space. Although we see evidence of iron in stars and planets, we don't see it in the interstellar medium. This is the 'missing iron' problem, and one possible explanation is that the iron being present in nanoparticles too small to see. Another is that iron is 'locked away' in silicate minerals, in quantities too low (less than 10%) to affect the spectral properties of the dust.
Using sol-gel to incorporate iron into the silicate structure requires special drying conditions and Dr Thompson and his team had previously developed a vacuum drying process. However this took several days to complete from start to finish.
The researchers, therefore, investigated whether they could speed up the production of analogue samples, and produce iron-bearing silicate dust, using an off-the-shelf microwave oven.
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