Astronomers Find Surprising Strength in Brown Dwarf Emissions

Brown dwarfs are often referred to as failed stars because they are too small to generate the nuclear fusion found at the core of bigger and brighter stars. They have also long been thought of as astronomical duds, emitting only weak X-rays and feeble reddish glows.

But in a report published in today’s Nature, a team led by Caltech graduate student and radio astronomer Edo Berger report strong radio emissions coming from a brown dwarf. The team observed LP944-20, a brown dwarf from which astronomers detected an X-ray flare in 1999. The newly detected flaring radio signals, or “whistles,” are 10,000 times stronger than expected from the strength of that X-ray flare. They are the first radio emissions ever detected from a brown dwarf.

The team suspects the strong emissions are possible because the failed star possesses a very weak magnetic field. The behavior of the brown dwarf, said Swiss astronomer Arnold O. Benz, indicates “that these dusky little objects have more surprises in store.”