Two such objects were discovered in a recent study

Nov 21, 2013 14:03 GMT  ·  By

Researchers with the University of Hertfordshire announce the discovery of two new brown dwarfs in our galaxy. These ancient objects are believed to be more than 10 billion years old, having formed when the Milky Way itself was just beginning to emerge.

Astronomers led by UH expert Dr. David Pinfield were able to measure the speed of these grown dwarfs, and determined that they are traveling at speeds around 100 to 200 kilometers (62 to 124 miles) per second. This is a much higher velocity than that of other stars in the Milky Way.

Interestingly, the team also found that these two objects were traveling faster than brown dwarfs identified in other studies. This may suggest that they are part of a previously-unknown population of ancient brown dwarfs in the Milky Way.

These objects are, in essence, failed stars. They were formed by gas clouds that did not have sufficient mass to lead to ignition during gravitational collapse. Usually, when such a cloud implodes, friction in the gas ignites it, leading to nuclear fusion. However, this only happens when enough gas is available.

On average, brown dwarfs reach a maximum mass equal to 7 percent that of the Sun. They produce no internal heat, and are very difficult to detect with optical telescopes. You can think of them as much larger and darker gas giants.

Details of the new discovery, and of its potential implications for understanding the Milky Way, were published in the latest issue of the Oxford University Press journal Monthly Notices of the Royal Astronomical Society.

The two objects the UH team found have temperatures ranging from 250 to 600 degrees Celsius (482 to 1,112 degrees Fahrenheit). Brown dwarfs tend to get colder the longer they live, astronomers explain.

This duo was discovered in data sent to Earth by the NASA Wide-field Infrared Survey Explorer (WISE) telescope. Accordingly, they are called WISE 0013+0634 and WISE 0833+0052, respectively.

“These two brown dwarfs may be the tip of an iceberg and are an intriguing piece of astronomical archaeology. We have only been able to find these objects by searching for the faintest and coolest things possible with WISE. And by finding more of them we will gain insight into the earliest epoch of the history of the Galaxy,” Pinfield says.

Studies estimate that the Milky Way contains a total of 70 billion dwarf planets, mostly in its thin disk.