The other seven dwarfs are essentially crumbs left over from the galactic mergers that made up the Milky Way about a billion years ago, Zucker explained. All of their stars are relatively old.
But the eighth dwarf, named Leo T, has formed new stars in the past few million years—very recently in cosmological terms.
In addition, Leo T contains large pockets of gas, giving it the potential to still form stars.
"This is basically the smallest, faintest, star-forming galaxy known by orders of magnitude," Zucker said.
Structure of the Universe
According to theoretical models, however, many more galaxies resembling Leo T may exist in the galactic neighborhood.
"Is this the tip of an iceberg?" Zucker asked.
The first of the faint new dwarfs came as a surprise, he noted, but it was soon proved to be one of many, perhaps dozens.
Additional dwarf galaxy finds could help scientists unravel the mystery of dark matter, a theoretical form of matter that does not give off or reflect light yet accounts for the vast majority of mass in the universe. (Related: "Dark Matter Mapped in 3-D, Scientists Report" [January 8, 2007].)
Nitya Kallivayalil, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, presented separate findings on the velocity of the Large and Small Magellanic Clouds at the AAS meeting.
The clouds are two of the Milky Way's closest—and previously known—dwarf galactic neighbors.
Commenting on the significance of both studies, she said: "Dwarf galaxies might really be the keys to understanding how structure forms in the universe."
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