A brown star with unusually red skies was discovered by University of Hertfordshire's Centre for Astrophysics Research astronomers
The extremely red appearance of ULAS J222711-004547 compared to other "normal" brown stars is what led researchers to the discovery. Using the VLT (Very Large Telescope) and additional data analysis techniques, the team of astronomers found that a thick layer of clouds in the brown dwarf's upper atmosphere was the cause of its unusual "red appearance."
"These are not the type of clouds that we are used to seeing on Earth. The thick clouds on this particular brown dwarf are mostly made of mineral dust, like enstatite and corundum," Federico Marocco, who led the research team from the University of Hertfordshire, said in a press statement. "Not only have we been able to infer their presence, but we have also been able to estimate the size of the dust grains in the clouds."
On earth red skies during sun rise and sun set are used to predict weather changes, but red skies on brown dwarfs suggest an atmosphere loaded with dust and moisture particles. The size of these dust grains influences the color of the sky. Interestingly, ULAS J222711-004547 has a very different atmosphere where the sky is always red.
The atmosphere of this recently discovered brown star is hotter than that of the giant planets in our solar system (like Saturn and Jupiter). It contains water vapor, methane and probably some ammonia. Mostly, it contains clay-sized mineral particles.
The researchers said that studying how such extreme atmospheres work can help them better understand the range of atmospheres that exist.
"Being one of the reddest brown dwarfs ever observed, ULAS J222711-004547 makes an ideal target for multiple observations to understand how the weather is in such an extreme atmosphere," Dr Avril Day-Jones, from the University of Hertfordshire's Centre for Astrophysics Research, who contributed to the discovery and analysis, said. "By studying the composition and variability in luminosity and colours of objects like this, we can understand how the weather works on brown dwarfs and how it links to other giant planets."
Brown dwarfs are better known as failed stars. They have a mass less than 8 percent of the Sun's mass and hence, are not massive enough to burn hydrogen at their core. They are too big to be called stars and too small to be planets. They also don't generate internal heat through nuclear fusion like stars. Owing to this, brown dwarfs are very cold and slowly fade away with time.
Lately, the number of brown dwarf discoveries has been phenomenal. In December last year, after studying two brown stars from the Luhman 16AB star system, researchers found the existence of another planet within the system.
Prior to that, two of the oldest brown dwarfs in the Galaxy were discovered by researchers from the University of Hertfordshire.
