An article published in “The Astrophysical Journal Supplement Series” describes a research on brown dwarfs, objects on the border between stars and planets. A team of researchers led by Jacqueline Fahery of the Carnegie Institution examined the characteristics of 152 young brown dwarfs and concluded that their atmospheres’ properties might be the behind their differences.

Brown dwarfs are a class of objects on the border between planets and stars. Their mass is significantly higher than that of Jupiter but much smaller than that of the Sun or even of a red dwarf star. Their mass is not enough to ignite the nuclear reactions typical of stars and it’s for this reason that brown dwarfs are considered failed stars.

For their characteristics, brown dwarfs may offer clues to the evolution of stars and also on that of planets. That’s one reason why in recent years a lot of research are focusing on these objects. The term research should be taken in some cases in a literal way because astronomers are still learning how to find them and their uneven distribution is another object of study.

Another reason for interest in brown dwarfs is the fact that they too can have planets orbiting them in miniature solar systems that can be studied more easily than those in which there is a star. That’s because brown dwarfs don’t emit light like stars but only faint infrared radiation so both them and their planets can be observed without the problem of shielding the instruments from starlight.

The studies regarding brown dwarfs showed that the temperature on their surface ranges widely because it can be close to that of a star while in other cases is at levels typical of a planet. This has consequences on its atmosphere’s structure and properties, a further difference besides mass, age and chemical composition.

The researchers identified the areas of space where many of the brown dwarfs they examined formed and this allowed them to rule out the differences in age and chemical composition as possible causes of the variability among these objects. In the end atmospheric conditions, meaning weather phenomena or differences in the clouds composition and structure, remained as the main suspect.

In the areas where the brown dwarfs identified by the researchers formed the presence of exoplanets was also discovered. This confirms one of the benefits that can come from the study of brown dwarfs because the results of this research can be extended to the giant planets that orbit stars and therefore are more difficult to study.