Context

A team of astronomers has discovered that the closest known brown dwarf, Luhman 16A, shows signs of cloud bands similar to those seen on Jupiter and Saturn.

About

What are Luhman 16A?

• Luhman 16A is part of a binary system containing a second brown dwarf, Luhman 16B.
• At a distance of 6.5 light-years, it's the third closest system to our Sun after Alpha Centauri and Barnard's Star.
• Both brown dwarfs weigh about 30 times as much as Jupiter.
• Despite the fact that Luhman 16A and 16B have similar masses and temperatures (about 1,900° F or 1,000° C), and presumably formed at the same time, they show markedly different weather.
• Luhman 16B shows no sign of stationary cloud bands, instead exhibiting evidence of more irregular, patchy clouds.
• Luhman 16B therefore has noticeable brightness variations as a result of its cloudy features, unlike///Luhman 16A.
  
  

Brown dwarfs Brown dwarfs are objects heavier than planets but lighter than stars, and typically have 13 to 80times the mass of Jupiter. They do not have enough mass to produce energy by nuclear fusion. Rather, the small amount of energy emitted by these objects comes almost exclusively from the heat stored in them during the collapse of the parent gas cloud from which they formed. Brown dwarfs therefore gradually cool and fade with cosmological time.

The research

• The researchers used an instrument on the Very Large Telescope in Chile to study polarized light from the Luhman 16 system.
• Polarization is a property of light that represents the direction that the light wave oscillates. Polarized sunglasses block out one direction of polarization to reduce glare and improve contrast.
• This is the first time scientists have used the technique of polarimetry to determine the properties of atmospheric clouds outside of the solar system, or exoclouds.

How these findings are significant?

• Subsequently, many astronomers detected polarisation of brown dwarfs. But what is special in the newest study of Luhman 16 is that the researchers have found the actual structure of the clouds — that they form bands over one of the pair (Luhman 16A) of brown dwarfs.
• Understanding the cloud system over a brown dwarf can shed light on the pressure, temperature and climate on the surface of the celestial body.