Using data from NASA's Wide-field Infrared Survey Explorer (WISE), astronomers have detected two ancient "failed stars" that are likely 10 billion years old. The discovery of the ancient pair has led to an estimate that there are likely billions of these previously unseen brown dwarfs barreling through our galaxy at high speed.
The University of Hertfordshire astronomers, led by David Pinfield, clocked the two brown dwarfs traveling at a breakneck velocity of 100-200 kilometers per second, far faster than younger stars and brown dwarfs. WISE 0013+0634 and WISE 0833+0052 were spotted through the detection of their very faint infrared signals in the constellations Pisces and Hydra, respectively.
ANALSIS: Do ‘Ultracool' Brown Dwarfs Surround Us?
Brown dwarfs form the stellar bridge between massive planets and small stars. They possess characteristics of both stars and planets, but cannot be defined as either. Brown dwarfs are too small to sustain nuclear fusion in their cores, hence the "failed star" moniker, but they lack material stratification through their bodies, so they don't fall into the planetary category either - they could just as easily be nicknamed "overachieving planets." As brown dwarfs are cool objects - these two new discoveries are thought to have temperatures between 250-600 degrees Celsius (520-870 Kelvin or 480-1,100 Fahrenheit) - only the most sensitive of infrared observatories can detect their weak infrared emissions.