UCDs are merged stellar super-clusters (e.g.  Most BCD galaxies are also classified as dwarf irregular galaxies or as dwarf lenticular galaxies. They consume gas intensely, which causes their stars to become very violent when forming. Now we know that the result was wrong and that DF44 is a typical dwarf galaxy. , Dwarf galaxy UGC 685 taken by Hubble. One theory states that most galaxies, including dwarf galaxies, form in association with dark matter, or from gas that contains metals.  It is theorised that these are the cores of nucleated dwarf elliptical galaxies that have been stripped of gas and outlying stars by tidal interactions, travelling through the hearts of rich clusters. They are thought to be on the order of 200 light years across, containing about 100 million stars. Context. In total, this study includes 380 stars in Fornax, Sagittarius, Sculptor, Sextans, Carina, Ursa Minor, Draco, Reticulum II, Bootes I, Ursa Major II, Leo I, Segue I, and Triangulum II. A new statistical study sheds light on the so-called 'ultra-compact dwarf galaxies' (UCDs). It is theorised that these are the cores of nucleated dwarf elliptical galaxies that have been stripped of gas and outlying stars by tidal interactions, travelling through the hearts of rich clusters. Because they are composed of star clusters, BCD galaxies lack a uniform shape. The galaxies' stars are all formed at different time periods, so the galaxies have time to cool and to build up matter to form new stars. There are several hypotheses for their origin: 1. Astronomers used Hubble to measure the ages of the stars in Leo IV and two other ultra-faint dwarf galaxies. We propose that there is an evolutionary link between ultra-compact blue dwarf galaxies (UCBDs) with active star formation and nucleated dwarfs based on the results of numerical simulations of dwarf–dwarf merging. These galaxies were located in the Leo Ring, a cloud of hydrogen and helium around two massive galaxies in the constellation Leo. The small and faint star-starved dwarf galaxy, Leo IV, is one of more than a dozen ultra-faint dwarf galaxies found lurking around the Milky Way. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is sometimes classified as a dwarf galaxy; others consider it a full-fledged galaxy. A 2007 paper has suggested that many dwarf galaxies were created by galactic tides during the early evolutions of the Milky Way and Andromeda. As time passes, this star formation changes the shape of the galaxies. Recent observations suggesting a high dark matter content and a steep spatial distribution within groups and clusters provide new clues as to their origins. , Because of their small size, dwarf galaxies have been observed being pulled toward and ripped by neighbouring spiral galaxies, resulting in galaxy merger. Ultra-faint galaxies, the subject of Keith Bechtol's feature article in the March 2017 issue of Sky & Telescope, are not easy to find.While Harlow Shapley spotted the Fornax and Sculptor dwarf galaxies in 1938 by examining photographic plates, the darker companions to the Milky Way Galaxy have required modern, statistical methods to suss out. I present proper-motion measurements based on Gaia DR2 for 17 ultra-faint dwarf galaxies within 100 kpc of the Milky Way. In fact, two of these objects in the southern night sky, called the Magellanic Clouds, are so large that they are visible to the naked eye. Nor could it be produced in cosmological simulations. These galaxies are dominated by dark matter, an invisible substance that makes up the bulk of the universe’s mass. Dwarf galaxies' formation and activity are thought to be heavily influenced by interactions with larger galaxies. In a hierarchical formation scenario, these objects are the building blocks of more massive galaxies and are believed to have been even more numerous at earlier times.