Astronomers have, for the first time, found evidence of water clouds on a body lying outside of the solar system.
The clouds of water, which were discovered around a very cold object called WISE 0855, were to be reported in the Astrophysical Journal Letters.
WISE 0855, which is located 7.2 light-years away from the Earth, may resemble gas giants such as the Solar System's Jupiter and Saturn, but it is in fact a brown dwarf.
Brown dwarfs are failed stars whose life started out just like most stars do, but they never gained enough mass to generate nuclear fusion reactions that are needed to make the stars shine.
The object was discovered in 2014 with help from data gathered using the Wide-field Infrared Survey Explorer (WISE), a NASA infrared-wavelength astronomical space telescope. A 2014 study that looked at limited photometric data found evidence that WISE 0855 has water clouds in its atmosphere.
In the new study, Andrew Skemer, from the University of California, Santa Cruz, and colleagues used the Gemini North telescope in Hawaii to study the object for 13 nights allowing them to obtain its infrared spectrum. The observations helped shed light on the object's chemical composition as well as provided evidence that WISE 0855 hosts clouds of water or ice.
"Our spectrum reveals the presence of atmospheric water vapor and clouds, with an absorption profile that is strikingly similar to Jupiter," the researchers wrote in their study.
"The spectrum is high enough quality to allow the investigation of dynamical and chemical processes that have long been studied in Jupiter's atmosphere, but now on an extrasolar world."
Skemer and colleagues have also confirmed the temperature of the object is about minus 10 degrees Fahrenheit. Skemer said that an object this cold is expected to have water clouds and they have so far found the best evidence that the brown star does have clouds of water.
"WISE 0855 is our first opportunity to study an extrasolar planetary-mass object that is nearly as cold as our own gas giants," Skemer said.
The spectrum of WISE 0855 looks very similar to the water absorbing features observed in the atmospheres of Jupiter albeit there are some differences such as the amount of phosphine. The compound, which is made up of phosphorus and hydrogen, abounds in Jupiter, but WISE 0855 does not have it.
The absence of phosphine suggests that the brown star has a less turbulent atmosphere compared to that of Jupiter.
