According to scientists' estimates, half of the stars in the galaxy never got enough mass together to ignite their nuclear engines.
These so-called "failed stars," or brown dwarf stars, are dim, cool and difficult to study at their most mature stage. Finding them in their infancy has been nearly impossible.
But astronomers have their first good prospect — twins actually — found in a dark cloud known as Barnard 213, which lies about 450 light-years from Earth in a region bursting with young objects.
If confirmed, the discovery could retire doubts about whether brown dwarfs form like stars from the gravitational collapse of gas clouds, or like planets, which pile up rocky material from a dust disc until they have the gravitational strength to attract gas as well.
"It comes down to mass and formation mechanisms," David Barrado, with the Centro de Astrobiologia in Madrid, Spain, told Discovery News.
The candidate baby brown dwarfs are wrapped in a cocoon of dust, indicating a star-like formation process.
If brown dwarfs form like stars, it raises the prospect that they could host planetary systems, said Michael Warner, project scientist with NASA's Spitzer infrared space telescope.
"It's conceivable that a brown dwarf could be closer than the nearest star," Warner told Discovery News.
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Month in Space: January 2014
The first brown dwarfs were discovered in 1995, setting off a debate about how they formed. Barrado and colleagues embarked on a methodical search for a young brown dwarf, hoping to resolve the debate.
They began by scrutinizing objects observed by NASA's Spitzer space telescope. The team sought out objects radiating less than about one tenth the luminosity of the sun and were embedded in dense nebular cores.
From that candidate list, the researchers turned to other observatories to determine how much energy the objects were emitting across the entire spectra. They used that to rule out other comic entities, such as distant galaxies and quasars.
"We got the data in different wavelengths so we could measure the proper motion," Barrado said. "(The candidate proto brown dwarf) is moving, just a tiny fraction, so we know it's not a galaxy."
Follow-up studies are under way to analyze the suspect baby brown dwarfs for chemical signatures and other properties.
"We're in the process of getting spectroscopy," Barrado said. "That will show us the fingerprints of these objects — what is really there — and will give us some additional clues about its real nature."
Barrado's work is published in the September issue of Astronomy and Astrophysics.
