Credit: ESA/Hubble & NASA
There are many galaxies in the Universe and although there is plenty
of room, they tend to stick together. The Milky Way, for example, is
part of a large gathering of over fifty galaxies known as the Local Group. Galaxy groups like this come together to form even larger groups called clusters which can congregate further still to create mammoth superclusters.
The
sphere of space surrounding our galaxy is known as the Local Volume, a
region some 35 million light-years in diameter and home to several
hundred known galaxies. The subject of this new NASA/ESA Hubble Space
Telescope image, a beautiful dwarf irregular galaxy known as PGC 18431, is one of these galaxies.
This
image shows PGC 18431 smudged across the sky, but it wasn’t imaged
purely for its looks. These Hubble observations were gathered in order
to probe how Local Volume galaxies cluster together and move around.
Hubble’s high resolution allows astronomers to explore star populations
within these moderately distant galaxies — specifically, stars known as tip of the red-giant branch
stars — in order to get an idea of the galaxy’s composition and,
crucially, its distance from us. Knowing galactic distances enables us
to accurately map a galaxy sample in three dimensions, a method key to
understanding more about our cosmic neighbours, and to dismiss
perspective and line-of-sight illusions.
Source: ESA/Hubble - Space Telescope
