Picture of the month

This image might appear to show a large empty patch in the sky without any stars, but in reality it shows a molecular cloud in our galaxy obscuring our view. A high concentration of dust and molecular gas absorbs almost all of the visible light emitted from the stars behind it, producing the black patch. The molecular cloud shown in this image is known as Barnard 68, which is relatively nearby at about 500 light-years away and is half a light-year across. Molecular clouds are almost impenetrable for radiation in the visible part of the spectrum, but the stars behind them can be observed in the infrared. Furthermore, observations of these objects at submillimetre wavelengths can show stars forming in molecular clouds (a href=”http://cerncourier.com/cws/article/cern/69627″>CERN Courier September 2017 p15). The stars form as dense regions of the cloud collapse into themselves to form areas dense enough to initiate the burning of hydrogen.

About the author

Compiled by Merlin Kole, Department of Particle Physics, University of Geneva.