Hubble telescope finds galaxy 30 million light-years from Milky Way
Astronomers have accidentally discovered a dwarf galaxy in our ‘cosmic backyard’ using the Hubble Space Telescope. The dwarf galaxy is ‘only’ thirty million light-years from the Milky Way.
The discovered dwarf galaxy is nicknamed Bedin 1 by the astronomers. It is a relatively small, elongated galaxy with a length of 3000 light-years, which is only a fraction of the size of the Milky Way. Bedin 1 is also a system that emits very little light. Based on these properties, the discoverers classified the galaxy as a dwarf spheroidal galaxy.
Bedin 1 was accidentally discovered by an international team of astronomers studying white dwarf stars in NGC 6752, a globular cluster of the Milky Way galaxy located 13,000 light-years from Earth. The purpose of these observations was to determine the age of NGC 6752 via the white dwarf stars. Hubble’s ACS camera revealed a compact collection of stars in the outer rim of the globular cluster.
Based on an analysis of their luminosity and temperatures, it was concluded that the stars do not belong to NGC 6752 and are millions of light-years behind this cluster. Bedin 1 is located thirty million light-years from the Milky Way Galaxy and two million light-years from NGC 6744, a galaxy closest to Bedin 1 and believed to be the parent galaxy. This makes Bedin 1 perhaps the most isolated small dwarf galaxy found to date. It is also a very old system, with an age of thirteen billion years. The researchers describe it as an ‘astronomical equivalent of a living fossil from the early universe’.
The discovery of Bedin 1 is quite special, because such faint objects are usually not visible in most images taken with the Hubble Space Telescope. In addition, a limited part of the sky is photographed with the telescope. The future WFIRST telescope will cover a much larger area, potentially discovering more galaxies. NGC 6752 is also visible to the naked eye in the dark.
The bottom image shows NGC 6752; the right image shows the full angle of view of the Hubble telescope and the top left image shows the part of Bedin 1. The left image shows a collection of less bright stars that are relatively close together behind the brighter stars of NGC 6752; this is Bedin 1.