Free Astronomy Magazine March-April 2016

SPACE CHRONICLES freak! IC 1613 contains very little cosmic dust, allowing astronomers to explore its contents with great clarity. This is not just a matter of ap- pearances; the galaxy’s cleanliness is vital to our understanding of the Universe around us. IC 1613 is a dwarf galaxy in the constellation of Cetus (The Sea Monster). This VST image shows the galaxy’s unconven- tional beauty, all scattered stars and bright pink gas, in great detail. German astronomer Max Wolf discov- ered IC 1613’s faint glow in 1906. In 1928, his compatriot Walter Baade used the more powerful 2.5-metre telescope at the Mount Wilson Ob- servatory in California to successfully make out its individual stars. From these observations, astronomers fig- ured out that the galaxy must be quite close to the Milky Way, as it is only possible to resolve single pin- prick-like stars in the very nearest galaxies to us. Astronomers have since confirmed that IC 1613 is in- deed a member of the Local Group, a collection of more than 50 galaxies that includes our home galaxy, the Milky Way. IC 1613 itself lies just over 2.3 million light-years away from us. It is relatively well-studied due to its proximity; astrono- mers have found it to be an ir- regular dwarf that lacks many of the features, such as a starry disc, found in some other dimin- utive galaxies. However, what IC 1613 lacks in form, it makes up for in tidi- ness. We know IC 1613’s dis- tance to a remarkably high precision, partly due to the unusually low levels of dust lying both within the galaxy and along the line of sight from the Milky Way — something that enables much clearer ob- servations. Cosmic dust is made of various heavier elements, such as car- The Milky Way’s clean and tidy galactic neighbour by ESO T his image, captured with the OmegaCAM camera on ESO’s VLT Survey Telescope in Chile, shows an unusually clean small galaxy. IC 1613 contains very little cos- mic dust, allowing astronomers to explore its contents with great clarity. [ESO] M any galaxies are chock-full of dust, while others have occasional dark streaks of opaque cosmic soot swirling in amongst their gas and stars. How- ever, the subject of this new image, snapped with the OmegaCAM cam- era on ESO’s VLT Survey Telescope in Chile, is unusual — the small galaxy, named IC 1613, is a veritable clean