Map of the Obscuration in the Dark Cloud B68

This photo shows the degree of obscuration in the area around B68, as an iso-extinction map. It is based on measurements of background stars. The angular resolution is 10 arcsec. The outermost contour corresponds to a visual extinction of 4 magnitudes (this means that visible light is dimmed/obscured by a factor of 40) and increases in steps of 2 magnitudes (a factor of 6.3) up to 35 magnitudes at the centre (an obscuration factor of 10 14 or 100 million million times)! Because the dust extinction is tracing the main mass component of this cloud, molecular hydrogen (H 2), this map is also a very good representation of the distribution of mass inside B68.