A team led by astronomers from the University of California, Santa Cruz found strong evidence of water clouds or water ice in a brown dwarf called WISE 0855. This marks the first time such clouds have been discovered outside of our own solar system.
WISE 0855, located 7.2 light years away, is the coldest known object outside of the solar system. It is extremely faint, so it can only be seen at infrared wavelengths. Hence, the research team needed to use the Gemini North telescope in Hawaii and the Gemini Near Infrared Spectrograph to assess the brown dwarf’s chemistry and composition.
As stated in the study currently available online in Astrophysical Journal Letters, the brown dwarf was previously speculated to have water clouds in 2014 but data was too limited to confirm this theory. However, after assessing the brown dwarf with the technology for a total of 14 hours over 13 nights, they determined that WISE 0855’s atmosphere is dominated by water clouds.
“It’s five times fainter than any other object detected with ground-based spectroscopy at this wavelength,” adds the study’s first author Andrew Skemer, an assistant professor of astronomy and astrophysics at UC Santa Cruz. “Now that we have a spectrum, we can really start thinking about what’s going on in this object. Our spectrum shows that WISE 0855 is dominated by water vapor and clouds, with an overall appearance that is strikingly similar to Jupiter.”
Scientists say that WISE 0855 is a failed star because it did not gain enough mass to start nuclear fusion reactions that make other stars shine. It resembles Jupiter although it has five times more mass than the gas giant. Jupiter is 130 degrees Kelvin while the brown dwarf is 250 degrees Kelvin.
WISE 0855 has the same water absorption features as Jupiter. Despite being similar in some ways, scientists assert that they do not have the same amount of phosphine in their atmospheres.
Phosphine is a compound that indicates turbulence in the atmosphere as a result of reaction between the planet’s interior and outer atmosphere. WISE 0855 has less of this compound than Jupiter, implying that the brown dwarf has a less turbulent atmosphere.