One of the smallest brown dwarf stars we've ever seen

Too large to be considered planets, but too small to spark the internal nuclear reactions necessary to become full-blown stars, brown dwarfs — aka "failed stars" — are of particular interest to astronomers because of what they can teach us about planetary and star formation.

Now, astronomers have discovered more than two dozen previously unknown brown dwarfs in a pair of nearby star clusters, including one that researchers claim ranks among the smallest ever discovered. The researchers' findings continue to blur the line dividing our universe's smallest stars and biggest planets.

The majority of the newly discovered brown dwarfs weigh in at around 20 Jupiter masses — what has long been considered the low end of the known mass-range for brown dwarfs. Below this cutoff, astral bodies tend to adopt a planetary identity, while the nuclear fusion of atoms required to become a star is thought to occur in bodies in excess of 75 Jupiter masses.

But one of the recently-discovered brown dwarfs weighs in at just six Jupiter masses, placing it firmly outside this previously established range.

"Its mass is comparable to those of giant planets, yet it doesn't circle a star," said Aleks Scholz, lead author of one of the forthcoming papers describing the team's findings. "How it formed is a mystery."

"Our findings suggest once again that objects not much bigger than Jupiter could form the same way as stars do," echoed University of Toronto's Ray Jayawardhana, lead investigator of the survey that found the new brown dwarfs. "In other words, nature appears to have more than one trick up its sleeve for producing planetary mass objects."

You can read more about the researchers' curious findings over at SPACE.com
Top image by Jon Lomberg via SPACE.com