Study finds common trait among distant planets where exotic clouds form

A new study has found a common trait among distant worlds where exotic clouds form. The research reveals the temperature range at which silicate clouds can form and are visible at the top of brown dwarf - celestial bodies that are larger than a planet but not big enough to become a star - atmospheres.

The finding was derived from observations by NASA's retired Spitzer Space Telescope of brown dwarfs. Before this study, Spitzer data already suggested the presence of silicate clouds in a handful of brown dwarf atmospheres.

For this research, astronomers gathered more than 100 of those marginal detections and grouped them by the temperature of the brown dwarf. All of them fell within the predicted temperature range for where silicate clouds should form: between about 1,900 degrees Fahrenheit (about 1,000 degrees Celsius) and 3,100 F (1,700 C). While the individual detections are marginal, together they reveal a definitive trait of silicate clouds.

"We had to dig through the Spitzer data to find these brown dwarfs where there was some indication of silicate clouds, and we really didn’t know what we would find. We were very surprised at how strong the conclusion was once we had the right data to analyze," said Genaro Suárez, a postdoctoral researcher at Western University and the lead author of the new study.

Scientists used data from our retired Spitzer telescope to study the atmospheric conditions of numerous brown dwarfs, objects larger than a planet but not big enough to become a star, to understand how some form layers of clouds made of rock. Read more: https://t.co/s5oPtJrOQU pic.twitter.com/RHz7gK2Z8l

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In atmospheres hotter than the top end of the range identified in this study, silicates remain a vapor. Researchers think that silicate clouds exist deep in Jupiter's atmosphere. Silicate clouds can't rise higher because when it's too cold they turn into rain or sink lower in the atmosphere. At higher temperatures, the planet's ammonia and ammonium hydrosulfide clouds would vaporize and the silicate clouds could potentially rise to the top.