Free Astronomy Magazine May-June 2019

53 MAY-JUNE 2019 large galaxy host, NGC 6744. This makes it possibly the most isolated small dwarf galaxy discov- ered to date. From the properties of its stars, as- tronomers were able to infer that the galaxy is around 13 billion years old — nearly as old as the Universe itself. Be- cause of its isolation — which resulted in hardly any interac- tion with other galaxies — and its age, Bedin 1 is the astronomical equiva- lent of a living fossil from the early Uni- verse. The discovery of Bedin 1 was a truly serendipitous find. Very few Hubble images allow such faint objects to be seen, and they cover only a small area of the sky. Future telescopes with a large field of view, such as the WFIRST telescope, will have cam- eras covering a much larger area of the sky and may find many more of these galactic neighbours. While dwarf spheroidal galaxies are not uncommon, Bedin 1 has some notable features. Not only is it one of just a few dwarf spheroidals that have a well established distance but it is also extremely isolated. It lies about 30 million light-years from the Milky Way and 2 million light- years from the nearest plausible and temperatures, the astronomers concluded that these stars did not belong to the cluster —which is part of the Milky Way — but rather they are millions of light-years more distant. Our newly dis- covered cosmic neighbour, nicknamed Bedin 1 by the as- tronomers, is a modestly sized, elongated galaxy. It measures only around 3000 light-years at its greatest ex- tent — a fraction of the size of the Milky Way. Not only is it tiny, but it is also incredibly faint. These properties led as- tronomers to classify it as a dwarf spheroidal galaxy. Dwarf spheroidal galaxies are defined by their small size, low-luminosity, lack of dust and old stellar populations. 36 galaxies of this type are already known to exist in the Local Group of Galaxies, 22 of which are satellite galaxies of the Milky Way. T his computer animation, using real astro- nomical data from the NASA/ESA Hubble Space Tele- scopes and from ground-based tele- scopes, allows us to fly through the globular cluster NGC 6752 and shows the newly discovered dwarf galaxy Bedin 1 be- hind it. [ESA/Hub- ble, M. Kornmesser] !