Brown Dwarf Duo System Puzzles Experts

Scientists from the Pennsylvania State University (Penn State) have recently discovered a new system of brown dwarfs orbiting a giant, dying star. Rather than clearing things up, the finding also served to deepen the mystery associated with brown dwarfs. It would appear that established astronomical knowledge is also false, as planets can apparently assemble themselves around their parent stars more quickly and efficiently than anyone thought possible before. Astronomers from several countries have been involved in the new astronomical observations.

“We have found two brown dwarf-sized masses around an ordinary star, which is very rare,” the Penn State Evan Pugh Professor of Astronomy and Astrophysics Alex Wolszczan says. The expert, who has also been the lead scientist on the new investigation, has collaborated with colleagues from the Torun Center for Astronomy, in Poland, and the Center for Exoplanets and Habitable Worlds. Details of their discoveries are published in the latest issue of the Astrophysical Journal. The parent star for the two brown dwarfs is called BD +20 2457. Experts say that the bloated celestial object is currently reaching the end of its burning cycle, and that it will come to an abrupt “death” within a few million years.

Brown dwarfs are already mysterious as it is. They tread the very fine line that separates small stars from large planets, and the jury is still out on what they actually are. The fact that they were discovered orbiting a star seems to lend more credence to the second hypothesis, but more studies are required before a conclusion can be drawn. Wolszczan says that the origin of brown dwarfs still remains a mystery. “If we find one brown dwarf, we are not sure where it came from. It could be either from the process of planet formation or it could be a direct product of star formation,” he says.

Finding two, however, is a different matter. This can only mean that they both formed from protoplanetary disks, which are the massive rings of debris that remain in the vicinity of a star just after it is formed. “If that is the case, then if we add up the minimum masses of these two objects, we know the disk had to be extremely massive,” the expert adds. The international team used the High Resolution Spectrograph instrument, on the Hobby-Eberly Telescope in West Texas, to make the recent observations. The study revealed that the two companions around BD +20 2457 were at least 21 and 13 times the mass of Jupiter.

“The lesson from this is that a combination of physical mechanisms may be responsible for making brown dwarfs. Instead of just growth by accretion (the steady accumulation of material), the dwarfs' own gravity may help them gather more mass and speed up their formation,” Wolszsczan concludes.