Seven of the new galaxies are gravitationally bound to our galaxy
Researchers from the Sloan Digital Sky Survey announced the discovery of eight new dwarf galaxies, seven of them satellites orbiting the Milky Way.
They resemble systems cannibalized by the Milky Way billions of years ago and help close the gap between the observed number of dwarf satellites and
theoretical predictions.
(MSNBC)-A recent sky survey has turned up eight new members in our Local Group of galaxies, including a new class of ultra-faint "hobbit"
galaxies and what might be the smallest galaxy ever discovered.
The Local Group is a collection of about 40 galaxies, of which the Milky Way and Andromeda are the dominant members. The rest of the galaxies are
mostly small satellites known as “dwarf galaxies” that are gravitationally bound to these two galaxies. The Large and Small Magellanic Clouds are
two of the Milky Way’s better known dwarf galaxies.
Seven of the new galaxies are gravitationally bound to the Milky Way, while the eighth appears to float freely in space, beyond our galaxy’s
grasp.
“They seem to be much fainter than anyone suspected galaxies could be before,” said study team member Daniel Zucker of Cambridge University.
“So rather than dwarf galaxies, we should perhaps call them ‘hobbit galaxies.’”
The dimness could be the result of stellar age, as seven of the new galaxies contain mostly old stars. Of these seven, two are located in the
constellation Canes Venatici, one in Bootes, one in Leo, one in Coma Berenices, one in Ursa Major and one in Hercules.
The eighth and most recently spotted galaxy is in many ways the most interesting. Dubbed Leo T, it is located about 1.4 million light-years away
from Earth, so far away that it floats freely in space, unperturbed by the Milky Way.
Unlike the other hobbit galaxies, Leo T includes both old and young stars. It also contains large amounts of neutral hydrogen gas — a prime
ingredient of star formation — suggesting it is still an active stellar nursery.
Because of its great distance, Leo T is also the dimmest of the new hobbits. “This is basically the smallest, faintest star-forming galaxy known, by
orders of magnitude,” Zucker said.
