Brown dwarfs may be as common as stars in the Milky Way galaxy, according to the astronomers behind a survey of a "nearby" star cluster:
It seems that for every star that ignites, there may be a failed star. A recent study by international researchers, including scientists at York University, found that the Milky Way may be home to 100 billion brown dwarfs — which matches the projected head count of 100 billion stars in our galaxy.
[...] The researchers performed an extensive survey of RCW 38, an ultra-dense star-forming cluster around 5,500 light-years away. Most stars that form in the region live fast, gain mass, and die young in a supernova explosion. But within the cluster, the researchers found the same ratio of brown dwarfs as in five other surveyed clusters going back to 2006, many without the same extreme conditions as RCW 38. In other words, there seems to be a fairly uniform distribution of brown dwarfs across the galaxy, regardless of environment.
"We've found a lot of brown dwarfs in these clusters. And whatever the cluster type, the brown dwarfs are really common," Alex Scholz, an astronomer at University of St. Andrews, said in a press release. "Brown dwarfs form alongside stars in clusters, so our work suggests there are a huge number of brown dwarfs out there."
Many nearby objects are brown dwarfs. Luhman 16, the third closest system to our own solar system, is comprised of two brown dwarfs about 6.6 light years away, yet was only discovered in 2013.
Also at the Royal Astronomical Society and Space.com.
(Score: 2) by HiThere on Saturday July 08 2017, @11:09PM (1 child)
IIUC, a brown dwarf never started a self-sustaining fusion reaction. That's why they are called "failed" stars. That's a reasonable argument for not calling them stars, but then you're just arguing about names, not about reality. (OTOH, the GP didn't specify *why* he didn't think they were stars, so maybe he has some other reason.)
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(Score: 1, Informative) by Anonymous Coward on Sunday July 09 2017, @12:53AM
Oh sure, brown dwarfs fuse nuclei, but they don't fuse hydrogen nuclei, so they're just not stars. And deuterium doesn't count as true hydrogen. </sarcasm>