Astronomers have discovered a brown dwarf star emitting flashes of light brighter than the Sun – even though it's not supposed to be able to do that.
Brown dwarves are also known as “failed stars” since they do not generate enough energy to support hydrogen fusion – a process that sustains a star’s brightness over millions of years. But brown dwarf 2MASS 0335+23 – catchy name – refuses to be a labelled a failed star.
By studying pictures of the star taken by NASA’s Kepler telescope, astronomers discovered that the star’s brightness would suddenly shoot up and get twice as bright for two to four minutes.
The flares were brighter than the Sun and happened a dozen times over a three-month period, according to an announcement made at a recent American Astronomical Society meeting.
“This brown dwarf is very young by star standards — only 23 million years old, John Gizis, professor at physics and astronomy at the University of Delaware, said. “It has lots of flares that are as hot as or hotter than the flares coming off full-fledged stars. This shows that the warmer brown dwarfs can generate flares from magnetic field energy just like stars.”
The brown dwarf has a surface temperature of 4,400°F, making it about half as hot as the Sun. Astronomers believe that colder brown dwarf stars cannot generate flares despite having magnetic fields.
Solar flares are caused by sudden changes in the magnetic fields in the Sun’s corona. The magnetic field energy is converted into kinetic energy, and passes on a massive surge of energy to the particles in the sun’s plasma which causes them to violently erupt from the Sun’s surface.
“These flares are very powerful — stronger than the sun’s. They show what the sun could do when it was younger. It’s like its acne is going away,” Gizis said of the sun, which is four billion years old, and considered to be middle-aged. ®