Hubble Telescope Finds Galaxy at 30 million light-years from Melkweg
Astronomers have accidentally discovered a dwarf galaxy in our ‘cosmic back garden’ with the Hubble space telescope. The dwarf system is ‘only’ thirty million light years from the Milky Way.

The discovered dwarf system gets the nickname Bedin 1 of the astronomers. It is a relatively small, elongated galaxy with a length of 3000 light years, which is only a fraction of the Milky Way. Bedin 1 is also a system that emits very little light. On the basis of these properties, the discoverers have classified the system as a dwarf-spheroidal galaxy .

Bedin 1 was accidentally discovered by an international team of astronomers who were studying white dwarf stars in NGC 6752, a spherical cluster of stars that is part of the Milky Way and is at a distance of 13,000 light-years from Earth. The purpose of these observations was to determine the age of NGC 6752 through the white dwarf stars. With the Hubble’s ACS camera, a compact collection of stars was visible in the outer edge of the globular cluster.

On the basis of an analysis of their brightness and temperatures, the conclusion was drawn that the stars do not belong to NGC 6752 and millions of light years are behind this cluster. Bedin 1 is thirty million light-years from the Milky Way and two million light-years from NGC 6744, a system closest to Bedin 1 and presumably the mother galaxy. With this, Bedin 1 is probably the most isolated, small dwarf galaxy that has been found so far. It is also a very old system, with an age of thirteen billion years. The researchers therefore describe it as an ‘astronomical equivalent of a living fossil from the early universe’.

The discovery of Bedin 1 is quite special, because such weak objects are usually not visible on most images made with the Hubble Space Telescope. Moreover, with the telescope a limited part of the sky is photographed. The future WFIRST telescope will cover a much larger part, with which more systems may be discovered. NGC 6752 is visible to the naked eye in the dark.

Bedin 1
The bottom picture shows NGC 6752; the right-hand image shows the full angle of view of the Hubble telescope and the image at the top left shows the part with Bedin 1. On the left image, behind the fierce stars of NGC 6752, a collection of less bright stars can be seen that are relatively close to each other; this is Bedin 1.