The search for the origin of today’s galaxies has always been one of the central tasks of astrophysics. The Hubble Deep Field had already demonstrated the change in the appearance of the universe over the last several billion years. Another long exposure from HST provided additional input for the developing theories. The image contained 18 irregular systems of stars, smaller than full-grown galaxies but still experiencing active stellar formation. All of them are located at roughly the same distance (about 11 billion light years) and are very close together, so that several future mergers appear likely. Are these “pregalactic blobs,” as they have been called by their discoverer, the building blocks of more recent galaxies and the proof that galaxies formed not at once, but from smaller fragments? Aside from the Hubble Deep Field, this image was one of Hubble’s longest exposures: WFPC2 had collected photons from a region in the northern constellation Hercules for 67 orbits.
KeywordsDark Matter Star Formation Hubble Space Telescope Star Cluster Dwarf Galaxy
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