Room For A Small One? New Galaxy Is Discovered Within ‘Local Group’
A joint Russian-American team report the discovery of a new galaxy located within close proximity to the Milky Way: using Hubble’s advanced camera for surveys (ACS), the dwarf spheroidal galaxy (dSph), named Kks3, is located approximately 7 million light years from Earth in the southern constellation of Hydrus. To date, this new find is rare: Kks3 is only the second dSph galaxy ever found within the local group, after a similar object, KKR25, was discovered by the same team in 1995.
Dwarf spheroidal galaxies are low mass, compact, structures devoid of any regenerating star forming material; for this reason they tend to have reduced luminosities, and are difficult to locate: ‘Finding objects like Kks3 is painstaking work, even with observatories like the Hubble Space Telescope’, says senior team member, Professor Dimitry Makarov’. However, due to their elusive characteristics researchers believe there might be large, undiscovered, populations of dSphs throughout the Universe—If found, this conjecture could have important ramifications for current models and ‘our ideas about the evolution of the cosmos’.
The ‘local group’ is a conglomeration of approximately 50 galaxies of various size and classification (elliptical, spiral and irregular). Each galaxy rotates around a central point of gravity, believed to be located somewhere between the Milky Way and Andromeda; the whole group forms a subordinate structure within the much larger, ‘Virgo super-cluster’, and is approximately 3.1 Mpc, or 10 million light years, in diameter (see diagram).
Until now, astronomers believed our region of space was sparsely populated although, with the discovery of Kks3, this idea may require updating: ‘we’re slowly building up a map of our local neighbourhood, which turns out to be less empty than we thought. It may be that are a huge number of dwarf spheroidal galaxies out there’, surmises Makarov’.
The future looks bright for astronomy, with continued searches for dSph galaxies set to continue; as Robert Massey, from the Royal Astronomical Society, outlines in his latest article: the search for dSph galaxies, although challenging to find, should become easier once the next generation of multiwave telescopes become operational (James Web Space Telescope – 2018 and European Extremely Large Telescope – 2024).
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