The tiny galaxy is
only 30 million light-years away but is so dark and distant that it was only
found while astronomers were looking for something else entirely. Scientists
made the discovery while they were using the Hubble Space
Telescope to look at the white dwarf stars in a globular cluster known as
NGC 672. They had hoped to use those stars to measure the age of the cluster.
But as they did so
they spotted the small set of stars on the edge of the area they were observing.
After analysis, they found the stars did not belong to the cluster they were
looking at – a part of the Milky Way – but were in fact millions of light-years
away from it.
The new discovery
has been nicknamed Bedin 1 and is a small but long galaxy. It measures only
3000 light-years across even at its longest point, making it just a fraction of
the size of our own Milky Way. It is dark as it is feint. Together, those properties
led astronomers to classify it as what is called a dwarf spheroidal
galaxy.
Such galaxies are
defined by their small size and dim light, as well as their lack of dust and
old stellar populations. Researchers have found 36 galaxies of this kind in our
nearby area, 22 of which are satellite galaxies around our own Milky Way.
Dwarf spheroidal
galaxies are not uncommon, but the newly discovered one is strange in a number
of ways. It is extremely isolated, about 30 million light-years from the Milky
Way and two million light-years from its nearest possible host – making it the
most isolated of any small dwarf galaxy ever found.
From studying its
stars, scientists found that the galaxy is around 13 billion years old, making
it nearly as old as the entire universe. Because it is so distant from any
other galaxies – and so has been left largely undisturbed – as well as its old
age, the astronomers refer to Bedin 1 as a fossil from the beginning of the cosmos.
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