Saturday, July 16, 2011
As reported here and a few other places, two brown dwarf stars have been discovered by the WISE infrared space telescope. These brown dwarfs are quite close, but unfortunately they are not closer-than-Alpha-Centauri-type close. The distance to them: 15 and 18 light years.
What does make brown dwarfs discovered at this distance interesting though is the reminder they give that we really don't know a lot about our close neighborhood unless the objects we're talking about are kind enough to emit their own light. Take that away and the only way to discover them is using infrared, or other clever methods such as those used to discover extrasolar planets.
The nearer one has made the list of nearest stars on Wikipedia, which lists all those up to about 16 light years. The nearest lone brown dwarf is somewhat closer, at 13 LY.
Is a brown dwarf a star? asks a discussion on the same page here. I am of the opinion that we should call them stars for short, and substellar objects when we want to be precise. Just like dwarf planets vs. planets - a dwarf planet is a type of planet so simply call Ceres a planet unless we want to specify what kind it is. Terrestrial planet, gas giant planet, dwarf planet.