Brown dwarfs have sand clouds


Clouds and their composition are very different, depending on their position. On Jupiter they are made of ammonia and ammonium hydrosulfide. On Mars they are carbon dioxide. If you move away from the Solar System then everything becomes different. An example is the upper atmosphere of brown dwarfs which have masses between those of stars and gas giant planets. With a Spitzer telescope , the experts saw that silicate clouds exist . They are minerals that include sand and rocks, accounting for more than 90% of the earth’s surface.


Analyzing the atmospheres of brown dwarfs and planets where silicate clouds can form can help us understand what it would mean to see in the atmosphere of an Earth-like planet in size and temperature.

Stanimir Metchev, professor at Western University Ontario, Canada




In order for such clouds to form, the silicates need to cool down, producing condensation . To make the rock vapor, the temperature needs to be warmer than water. This is the reason for hotter celestial bodies such as brown dwarfs. An experiment by the scholars on 113 spectra of as many brown dwarfs observed with the Spitzer gave the answer.

The data were grouped according to the temperatures relative to the spectrum of the observed brown dwarf. Here all the brown dwarfs were connected to the suitable temperature (between 1,000 and 1,700 degrees) for the birth of silicate clouds. If this temperature range is exceeded, the silicates remain vapor, otherwise below the clouds they turn into precipitation.


We dug into Spitzer’s archive data to find brown dwarfs where there was any indication of the presence of silicate clouds, and we didn’t really know what we would find.

Genaro Suárez, scientist at Western University Ontario and first author of the research



  • Sand clouds on brown dwarfs. The discovery thanks to the Spitzer telescopes (


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