By Miranda Chant July 9, 2022 7:15 AM
Researchers at Western University are gaining a new understanding of planetary atmospheres that could one day help determine whether another planet could host Earth-like life.
Using archived data from NASA’s now-removed Spitzer telescope, the researchers examined how clouds of small dust grains, known as silicates, form in brown dwarfs, celestial bodies lying between planets and stars.
“Understanding the atmospheres of brown dwarfs or hot planets where silicate clouds can form can also help us understand what we would see in the atmosphere of a planet that is closer to Earth in size and temperature,” he said. co-author of the study Stanimir Metchev, Canada Research. Chair of Extrasolar Planets at Western University.
Although brown dwarfs form like stars, they are not massive enough to initiate fusion, but they have atmospheres almost indistinguishable from those of gas-dominated planets, such as Jupiter, so they can be used as an analogue of the planet. ‘another, according to researchers. indicated.
Metchev and Western Science postdoctoral researcher Genaro Suárez gathered more than 100 marginal detections of silicate clouds in brown dwarfs observed by Spitzer during the first six years of his mission. They then grouped them by the temperature of the brown dwarf. All silicate clouds fell within the temperature range predicted for their formation, between about 1,000 and 1,700 C. This effectively revealed the previously unknown temperature range, a definite feature, in which silicate clouds can form and be visible with a telescope.
“We had to explore Spitzer data to find those brown dwarfs where there was some indication of silicate clouds, and we really didn’t know what we would find,” Suarez said. “We were very surprised at how strong the conclusion was once we had the right data to analyze.”
In warmer atmospheres than the upper end of the range identified in the study, silicates remain a vapor. Below the lower end, clouds will turn to rain or sink lower into the atmosphere, where the temperature is higher.
The findings have led Metchev and Suarez to believe that silicate clouds exist in the depths of Jupiter’s atmosphere, where the temperature is much higher than at the top. They cannot rise higher because at lower temperatures the silicates would solidify and cease to be in the form of a cloud.
“If the top of the atmosphere were thousands of degrees warmer, the clouds of ammonia and ammonium hydrosulfide on the planet would vaporize and the silicate clouds could rise to the top,” Metchev said.
In general, the finding provides significant data on the composition of the atmospheres of gaseous planets, which helps to understand the conditions of Earth-like planets around other stars.
“Our understanding of the atmospheres of the brown dwarf worlds could let us know how particular the Earth’s atmosphere is and, therefore, whether or not other worlds have conditions to host life as we know it on Earth.” said Suarez.
The study was recently published in the Monthly Notices of the Royal Astronomical Society.