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A team of astronomers has discovered a dim object 60 to 90 times as massive as
Jupiter roughly 13 light-years from Earth -- practically in our backyard. The object may be our closest
known brown dwarf, bolstering the belief that there are many celestial treasures left to find, even in our own cosmic neighborhood.More research is needed to determine if the object is in fact a brown dwarf -- essentially a small, failed star -- or if it is an active star that is relatively small and dim. The object sits alone in space, not part of any star system or cluster.
The nearest confirmed brown dwarf is 16 light-years away. The nearest known star is Proxima Centauri, at 4.2 light-years away. A light-year is the distance light travels in one year, about 5.88 trillion miles (9.7 trillion kilometers).
So what is it?
The object was found by Thierry Forveille of the Canada-France-Hawaii Telescope Corporation and French astronomer Xavier Delfosse. Eduardo Martin of the University of Hawaii analyzed the object with the Keck 1 Observatory, looking for evidence of lithium, a signature of all but the largest brown dwarfs. He found none.
"If this object is a brown dwarf, then it is the closest one, but we are not sure," said Martin. "It failed the lithium test, so it could be a very low-mass star [75 to 90 Jupiter masses] or a high-mass brown dwarf [60 to 75 Jupiter masses]."
Martin told SPACE.com that there might be several unknown brown dwarfs even closer, but they would be cooler, fainter and even tougher to spot.
"Determining how many brown dwarfs exist will tell us about where these objects come from and what is their contribution to the overall chemical and dynamical budget of the Milky Way," Martin said.
Brown dwarfs are thought to form when an interstellar cloud of gas and dust collapses under the weight of gravity. This is also how real stars, like our Sun, are born. Planets, on the other hand, are generally thought to form out of the leftovers of such a process. Scientists are currently grappling with the
confusing overlaps in definitions.100 billion brown dwarfs?
Other brown dwarfs have been discovered recently, but their distances have not yet been determined, according to Tom Geballe of the Gemini Observatory.
"I think it is likely that of the 20 or so cool brown dwarfs now discovered, one or two will be found to be this close or closer," said Geballe, who was not involved in the new study but
studies the strange objects.Geballe told SPACE.com that surveys done so far indicate brown dwarfs may be as prevalent as stars.
"If the [prevalence] of brown dwarfs and stars are about the same, then there are over 100 billion brown dwarfs in our galaxy," Geballe said, adding that it would then be logical to assume that at least one would be found at around 4.2 light-years away, the distance to the closest star.
In recent years, some scientists had suspected that brown dwarfs might account for unseen "
dark matter" that is presumed to pervade the universe. "This now appears to be ruled out," Geballe says. "There would need to be about 100 times more brown dwarfs than are being found to account for all of the dark matter."
Next page: See the object move through space
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